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PubMed1983

The 24-hour serum digoxin level as a prognosticator of dosage requirement in low-birth-weight (LBW) infants.

Eleven LBW infants were studied to assess the predictability of individual digoxin dosage requirement from a single serum digoxin concentration (SDC) at various times within the first dosing interval. The mean and SD of gestational age, weight and postnatal age were 31.6 +/- 3.5 wk, 1.51 +/- 0.47 kg and 3.7 +/- 2.1 days, respectively. Total body digoxin clearance (TBDC) in each infant was calculated from the computer-fitted biexponential equation describing each first-dose blood level curve. There was no correlation between the TBDC (99.5 +/- 37.0 ml/kg/hr) and the 6-hr SDCs (3.1 +/- 0.6 ng/ml) after the first dose (P greater than 0.20). Significant correlation of both 12- and 24-hr SDCs (2.8 +/- 0.6 and 2.3 +/- 0.5 ng/ml) after first dose with TBDC was found (r = -0.53, P less than 0.05 and r = -0.87, P less than 0.005, respectively). Good correlation (r = 0.88) of 1/dose (where dose = mg/kg/day to achieve a mean steady-state level of 2 ng/ml) with the 24-hr SDCs was also observed (P less than 0.005).

Computers↗
PubMed2000

Population-based, case-control study of HER2 genetic polymorphism and breast cancer risk.

BACKGROUND: Alterations of the HER2 (also known as erbB-2 or neu) proto-oncogene have been implicated in the carcinogenesis and prognosis of breast cancer. A polymorphism at codon 655 (GTC/valine to ATC /isoleucine [Val(655)Ile]) in the transmembrane domain-coding region of this gene has been identified and may be associated with the risk of breast cancer. We evaluated this hypothesis in a subgroup of women who participated in a large-scale, population-based, case-control study of breast cancer in Shanghai, China. METHODS: Genomic DNA from 339 patients with breast cancer and 361 healthy control subjects was examined for the Val(655)Ile polymorphism with a polymerase chain reaction-restriction fragment-length polymorphism-based assay. All study subjects completed a structured questionnaire during an in-person interview. All P values are from two-sided tests. RESULTS: We found that 25.1% of the case patients and 21.7% of the control subjects were heterozygous for the Val allele and 3.2% of the case patients and 0. 3% of the control subjects were homozygous for this allele (P =.005). Compared with women with the Ile/Ile genotype, women who had the Ile/Val or Val/Val genotype had an elevated risk of breast cancer (odds ratio [OR] = 1.4; 95% confidence interval [CI] = 1.0-2.0; P =. 05) after adjustment for age, educational level, study period, history of breast fibroadenoma, leisure physical activity, and age at first live birth. The risk was elevated even more among women who were homozygous for the Val allele (OR = 14.1; 95% CI = 1.8-113.4). The association was more pronounced among younger women (</=45 years) than among older women (>45 years). The adjusted OR associated with the Val allele was 1.7 (95% CI = 1.1-2.6) for younger women and 1.0 (95% CI = 0.5-1.9) for older women. CONCLUSIONS: Results of this study suggest that polymorphisms of the HER2 gene may be important susceptibility biomarkers for breast cancer risk, particularly among younger women.

Adult↗
PubMed2000

Obstetric risk factors for stress urinary incontinence: a population-based study.

OBJECTIVE: To evaluate obstetric and maternal risk factors for stress urinary incontinence. METHODS: We linked three national, Swedish, population-based registries with the use of unique personal identification numbers. All women born between 1932 and 1977 and operated on for stress urinary incontinence between 1987 and 1996 were identified from the Hospital Discharge Registry. This information was linked with the Medical Birth Registry (for the years 1973-1995), containing information on antenatal care, delivery, and the newborn, and the Fertility Registry (for the years 1932-1997), containing information on the number of children delivered by each Swedish woman. For determination of odds ratios (ORs) and approximate 95% confidence intervals (CIs), we used the Mantel-Haenszel method and a test-based method after suitable stratifications and exclusions. RESULTS: Diabetes mellitus, body mass index (BMI), age at first delivery, parity, birth weight, and epidural analgesia were positively associated with incontinence surgery. In contrast, cesarean delivery, forceps/vacuum extraction, and episiotomy were negatively associated with incontinence surgery. No association was found between surgery for stress incontinence and age at last delivery, smoking during pregnancy, level of education, multiple birth, large perineal tear, or breech presentation at any vaginal delivery. The OR for incontinence surgery was similarly decreased for nulliparous women and for uniparous women delivered by elective cesarean. CONCLUSION: Vaginal delivery, notably the first, is strongly associated with later surgery for stress incontinence, but the association is modified by maternal conditions and interventions during delivery. No association was found between surgery for stress incontinence and pregnancy per se.

Adult↗
PubMed1986

Childhood leukemia and infectious diseases in the first year of life: a register-based case-control study.

In the Netherlands, a nationwide register of children with leukemia formed the basis for a case-control study (1973-1980). Population controls were matched with the cases for the year of birth, sex, and place of residence at the time of diagnosis. The information was collected by mailed questionnaires addressed to the parents. The analyses concerned infectious diseases in the first year of life of children with acute lymphocytic leukemia and their controls. Common colds, periods of fever, and primary childhood infections showed relative risks (RR) of 0.8, 0.9, and 0.8, respectively, after adjustment for birth order, family size, social class, and residential space. Furthermore, fewer cases reported infectious diseases which required hospitalization in their first year of life (RR = 0.6, 95% confidence interval (CI) = 0.4-1.0). The general infection risk profile of children with acute lymphocytic leukemia is compatible with these findings: there were more first-born children among the patients (RR = 1.8; 95% CI = 1.1-2.7), more children from one-child families (RR = 1.4; 95% CI = 0.8-2.3), more children of parents with higher education (RR = 1.2; 95% CI = 0.9-1.5), and more rooms in patient's houses (RR = 1.4; 95% CI = 0.6-2.6).

Adolescent↗
PubMed2004

Occurrence and predictors of cesarean delivery for the second twin after vaginal delivery of the first twin.

OBJECTIVE: To estimate the occurrence and to assess clinical predictors of emergent cesarean delivery in the second twin after vaginal delivery of the first twin. METHODS: We conducted a population-based cohort study, using the 1995-1997 linked mother/infant twin data from the United States. The adjusted risk ratios and population attributable risks of clinical predictors of emergent cesarean delivery in second twins were estimated for the overall study sample and for those born at less than 36 or 36 weeks or more of gestation. RESULTS: Among the 61,845 second twin births with the first twin delivered vaginally, 5,842 (9.45%) were delivered by cesarean. The cesarean delivery rate was increased in infants born to mothers with medical or labor and delivery complications. Breech and other malpresentations were the most important predictors of emergent cesarean delivery for the second twin (population attributable risk 33.2%; 95% confidence interval 31.8%, 34.6%). Operative vaginal delivery of the first twin was associated with a decreased risk of cesarean delivery for the second twin. Prediction of emergent cesarean for the second twin by clinical factors was stronger in term births than preterm births. CONCLUSION: In the general population, the cesarean delivery rate for the second twin after vaginal delivery of the first twin is approximately 9.5%. With the presence of breech and other malpresentations, the need for emergent cesarean delivery of the second twin after vaginal delivery of the first twin is increased by 4-fold. LEVEL OF EVIDENCE: II-2

Adult↗
PubMed2005

Reproductive factors, hormone use and the risk of lung cancer among middle-aged never-smoking Japanese women: a large-scale population-based cohort study.

Although a link between female hormonal factors and the risk of lung cancer has been suggested, few studies have examined this association in detail. We investigated the associations between reproductive factors, hormone use and the risk of lung cancer in a population-based prospective study. Self-administered questionnaires were distributed to 44,677 lifelong never-smoking women in 1990-1994 to assess menstrual and reproductive factors and hormone use. After 8-12 years of follow-up, 153 lung cancer cases were diagnosed. Relative risk (RR) and 95% confidence intervals (CI) were calculated using the Cox proportional hazards model. Age at menopause, age at menarche, number of children, age at first live birth, breast feeding and use of hormones were not associated with a risk of lung cancer, either overall or among postmenopausal women or women with natural menopause. Compared to women with both late age at menarche (> or =16) and early age at menopause (< or =50), those with either early age at menarche or late age at menopause had a >2-fold, significant increase in the risk of lung cancer. Induced menopausal women with experience of hormone replacement therapy had a significantly elevated risk compared to naturally menopausal women without female hormone use, with an RR of 2.40 (95% CI 1.07-5.40). These findings suggest that both endogenous and extraneous estrogen may be involved in the etiology of lung cancer.

Cohort Studies↗
PubMed2001

Risk factors for epithelial borderline ovarian tumors: results of a Swedish case-control study.

OBJECTIVE: Borderline ovarian tumors have a favorable prognosis. Previous epidemiological studies indicate common risk factors for invasive epithelial ovarian cancers and borderline tumors, but it remains unresolved whether these tumors are precursors of invasive cancers or a separate disease entity. The objective of this population-based case-control study conducted in 1993-1995 was to examine reproductive and other factors in relation to the risk of borderline ovarian tumors. METHODS: Subjects were 193 histologically verified incident epithelial borderline tumor cases and 3899 randomly selected controls aged 50-74 years, whose data were collected through mailed questionnaires. Risk estimates were calculated by unconditional logistic regression. RESULTS: Ever parous women were at reduced risk, with odds ratios of 0.44 (95% confidence interval (CI) 0.26-0.75) for serous and 0.63 (95% CI 0.34-1.19) for mucinous tumors. No clear trends emerged for age at first birth, at menarche, and at menopause. Lactation reduced tumor risk. Oral contraceptive ever use conferred no protection, with odds ratios of 1.40 (95% CI 0.87-2.26) for serous and 1.04 (95% CI 0.61-1.79) for mucinous tumors. The odds ratio for serous tumors following unopposed estrogen ever use was 2.07 (95% CI 1.08-3.95), whereas no risk increase appeared with estrogens supplemented by cyclic or continuous progestins. Mucinous tumors were not associated with hormone replacement therapy. The odds ratio for serous tumors in the highest category of body mass index was 6.47 (95% CI 3.09-13.5). CONCLUSIONS: Increasing parity and lactation reduce the risk of borderline ovarian tumors in women aged 50-74, while no protection follows oral contraceptive use. Hormonal situations such as unopposed estrogen use and obesity, where estrogens are not counteracted by progestins, may increase the risk of serous tumors.

Aged↗
PubMed1986

Rhythm and conduction disturbances in isolated, congenitally corrected transposition of the great arteries.

The incidence and types of rhythm and conduction disturbances in 11 male and 6 female patients with congenitally corrected transposition of the great arteries and no other intrinsic complicating anomalies were studied. Patient age ranged from 5 to 54 years; follow-up ranged from 5 to 37 years. Surface electrocardiograms were recorded in each patient; 15 also underwent 24-hour Holter monitoring and 10 underwent electrophysiologic study. The conduction system of a 54-year-old woman who died suddenly, with complete atrioventricular (AV) block since age 30 years, was studied by serial histologic sections. Fifteen patients were asymptomatic and 2 reported repeated episodes of palpitation since childhood. Ten patients presented with a normal PR interval and 2 with first-degree AV block (12%). Five patients had complete AV block (29%), but none had had it at birth; first- and second-degree AV block preceded complete AV block in 2 patients. The morphologic pattern and duration of QRS suggested a junctional rhythm in 4 patients and an idioventricular pacemaker in 1 patient. Electrophysiologic studies confirmed that the complete AV block site was supra-Hisian in 2 patients and proximal to the His bundle bifurcation in 1 patient. However, histologic investigation disclosed fibrosis and disruption of the proximal nonbifurcating His bundle in the patient who died suddenly. In 2 patients with recurrent supraventricular tachycardia, electrophysiologic studies suggested reentry through James fibers (or dual AV nodal pathway) in 1 and the presence of a left lateral accessory AV pathway in the other. Holter monitoring showed a high incidence of ventricular arrhythmias.

Adolescent↗
PubMed1994

Coordinate regulation of tubulin and microtubule associated protein genes during development of hamster brain.

The present study documents the patterns of mRNA expression for 5 different tubulin genes and 4 of the structural microtubule-associated protein (MAP) genes during normal development of hamster forebrain. Northern blotting in conjunction with densitometric analysis was used to study changes in the levels of the mRNAs for alpha 1-tubulin, classes beta I-, beta II-, beta III- and beta IV-tubulin, as well as the mRNAs for tau, MAP1A, MAP1B and MAP2, using total RNA isolated from hamster forebrain at various embryonic (E) and postnatal (P) stages. Densitometric analyses of the autoradiograms from the Northern blots revealed that each of the tubulin genes exhibited distinct developmental patterns of expression, several of which appeared to be temporally correlated with the expression of specific MAP mRNAs. The beta I-, beta II- and beta III-tubulin mRNAs increased rapidly between late embryonic stages to birth, reached peak levels early in the first postnatal week, and declined thereafter. alpha 1-Tubulin mRNA was easily detected during embryonic stages, rose to peak levels at P7-P9 and then gradually declined. A similar pattern was seen for tau mRNA. After the first postnatal week, the size of the tau mRNA also shifted to a slightly larger size, presumably due to differential splicing. beta IV-Tubulin mRNA levels did not become significant until very late in postnatal development (3-4 weeks). MAP2 mRNA expression was unusual in that peak levels were reached at two different stages of development--an initial peak occurred in the first postnatal week, followed by a decline, and then a second rise occurred during the third and fourth postnatal weeks. The expression of the beta IV-tubulin mRNA coincided temporally with the second peak in MAP2 mRNA expression. MAP1B mRNA abruptly reached high levels at birth, remained abundant during the first two postnatal weeks, and then decreased. In contrast, MAP1A mRNA levels were low in the initial postnatal interval and increased only at very late developmental stages. The findings of a temporal correspondence in expression of high levels of tau and MAP1B with beta I-, beta II-, beta III- and alpha 1-tubulin mRNAs suggest that this profile of gene expression is one that endows greater plasticity to the neuronal cytoskeleton. Conversely, the transition to increased expression of beta IV-tubulin, MAP1A, and a larger tau mRNA species defines a portion of the molecular pattern that underpins the increased stability of neuronal form during maturation.

Animals↗
PubMed1983

Risk factors for breast cancer.

Since 1976, data were collected to evaluate risk factors for breast cancer in a hospital-based case-control study of 1185 women with breast cancer and 3227 controls. The risk of breast cancer increased with increasing age at first birth; this effect was not accounted for by parity. An early age at first birth appeared to reduce the risk relative to no pregnancy, whereas a late age at first birth was associated with a higher risk than not having a full-term pregnancy. High parity was associated with a reduction in the risk that was independent of that of age at first birth: for parity greater than or equal to 5, compared with parity 1-2, the relative risk estimate was 0.7 (95% confidence interval, 0.5-1.0). Late age at menarche was associated with a lower risk among premenopausal women but not among postmenopausal women. The relative risk decreased with increasing obesity among premenopausal women. Among postmenopausal women, the risk was higher among those who were obese, but there was no evidence of a trend with increasing body mass index. Risk did not vary materially according to history of abortion when gravidity was controlled. Risk was lower among postmenopausal women than among premenopausal women of the same age and increased with increasing age at menopause; bilateral oophorectomy reduced the risk more than hysterectomy alone. A positive history of benign breast disease, a positive family history of breast cancer, Jewish religion, and 12 or more years of education were each independently associated with an increased risk of breast cancer.

Adult↗
PubMed1990

The effect of a warm environment on respiratory water loss in fullterm newborn infants on their first day after birth.

Continuous measurements of respiratory water loss (RWL), oxygen consumption and carbon dioxide production were made in 21 fullterm infants on their first day after birth. The infants were first studied in incubators with a temperature of 32.5 degrees C and an ambient humidity of 50%. After an interval with stable conditions the incubator temperature was raised to 36.5 degrees C while the water vapour pressure was kept constant. When the rectal temperature had increased to 37.8 degrees C or when the infant had started to sweat, the relative humidity in the incubator was increased to 50%. At the start of the measurements mean RWL was 4.9 mg/kg min. On the average, RWL increased to a maximal value of 7.0 mg/kg min in the warm environment. Mean oxygen consumption only increased from 5.3 to 5.8 ml/kg min. This meant that when nursed in this warm environment the infants were able to increase their respiratory water loss by nearly 50% without a significant change in oxygen consumption.

Body Temperature↗
PubMed2005

Spectral analysis of electroencephalography in premature newborn infants: normal ranges.

Continuous EEG monitoring has not been used widely in neonatal intensive care, especially in the care of extremely premature infants, probably in part because of a lack of a reliable quantitative method. The purpose of this study was to quantify the EEG of the very premature infants just after birth by using spectral analysis and to describe the characteristics of the spectral signal when infants were clinically stable. Digital EEG recordings were performed on 53 infants who were < or =30 wk gestation for 75 min each day during the first 4 d after birth. Artefact was rejected manually after visual inspection of trace. The EEG was analyzed by manual measurement of interburst interval and automatically by spectral analysis using Fast Fourier Transformation. Spectral analysis generated the normal ranges of the relative power of the delta (0.5-3.5 Hz), theta (4-7.5 Hz), alpha (8-12.5 Hz), and beta (13-30 Hz) frequency bands, spectral edge frequency, and symmetry. The median (range) relative power of the delta band increased significantly from 68% (62-76%) on day 1 to 81% (72-89%) on day 4 (p=0.001). The interburst intervals became progressively shorter between days 1 [14s (10-25)] and 3 [8s (6-12)]; there were no significant differences between days 3 and 4. The relative power of the delta band seemed to be the most useful and repeatable spectral measurement for continuous long-term monitoring. However, automatic artefact rejection software needs to be developed before continuous quantitative EEG monitoring can be used in the neonatal intensive care environment.

Age Factors↗
PubMed1987

Inhibition of post-partum maternal behaviour in the rat by injecting an oxytocin antagonist into the cerebral ventricles.

Endogenous oxytocin released into the brain at parturition may stimulate the onset of maternal behaviour. In this study an attempt was made to block spontaneous maternal behaviour following natural delivery in Wistar rats by the injection of an antagonist of oxytocin into the cerebral ventricles. The analogue antagonist, d(CH2)5-8-ornithine-vasotocin, was administered by injection into a chronically implanted cannula in the right lateral ventricle at hourly intervals, beginning immediately after the expulsion of the first pup. The antagonist did not interfere with the normal progress of parturition or birth-related behaviours. After delivery of the last pup, mothers rested for 40 min in the test cage with the pups having been removed. Four pups and standard nesting material were then presented. Latency to pup carrying and duration of pup manipulation, nest building, and time spent on the nest with the pups, as well as duration of autogrooming and general activity were determined. Saline-injected controls started gathering the pups immediately and usually showed all elements of maternal behaviour within 10 min. Antagonist-treated mothers showed a marked delay in the onset of pup grouping and other maternal behaviours. At the end of 1 h, two out of six mothers had not yet picked up a single infant. Pups left overnight with their mothers were gathered into the nest and suckled, and no long-term effects of the antagonist were evident on retesting. The effectiveness of oxytocin antagonist in suppressing the rapid onset of post-partum maternal behaviour supports the hypothesis that centrally released oxytocin is involved in this process.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1976

Quality of care given to first time birth control patients at a free clinic.

In an empirical study of the quality of care at a free clinic, criteria for optimal care for female first visits for birth control were established and 100 charts were reviewed, 50 in April 1974 and 50 in April 1975 with an interval in between of in-service training accompanied by new medical forms and procedures. An encouraging improvement in record keeping was observed. The authors feel it is important that free clinics concentrate on quality as well as quantity and accessibility of care.

Adult↗
PubMed2003

Comparison of arthroscopic findings with magnetic resonance imaging and arthrography in children with glenohumeral deformities secondary to brachial plexus birth palsy.

BACKGROUND: Characterization of glenohumeral deformities secondary to brachial plexus birth palsy with plain radiography is difficult because the glenohumeral joint does not completely ossify until puberty. The purpose of this study was to compare the findings on magnetic resonance imaging and arthrography with those on arthroscopy to better understand the roles of these methods in the evaluation of glenohumeral development in this condition. METHODS: Eighty-four children who ranged in age from seven months to thirteen years and six months had glenohumeral arthrography while they were under general anesthesia for operative treatment of an internal rotation contracture. Thirty-six children also received magnetic resonance imaging with use of cartilage-sensitive axial gradient-echo sequences. Thirty-seven children were evaluated arthroscopically. RESULTS: Arthrography showed a concentric glenohumeral joint in thirty-three children, a flat glenoid in eight, a biconcave glenoid in seventeen, and a pseudoglenoid in twenty-six. Thus, 61% (fifty-one) of the eighty-four children with an internal rotation contracture had a substantial deformity. The severity of the contracture was associated with the existence and the type of the deformity (p = 0.001). Magnetic resonance imaging showed greater detail than arthrography did in defining the severity of the deformity in both the glenoid and the humeral head. The thirty-seven children who were examined arthroscopically showed a progression from those who had a concentric, conforming joint to those who had a markedly deformed joint with a bifurcated glenoid and a flattened, oval-shaped humeral head that articulated with the posterior aspect of the glenoid. Irregularities and cavitation of the anterior aspect of the glenoid were common. The subscapularis and rotator interval tissue were the primary sites of contracture. CONCLUSIONS: Profound glenohumeral deformities secondary to brachial plexus birth palsy are commonly seen within the first two years of life. The information provided by imaging studies is helpful in defining the natural history of this condition and in determining the success of surgical intervention.

Adolescent↗
PubMed1977

[Levels of osteotrophic mineral elements (total calcium, inorganic phosphorus and magnesium) in the blood plasma of calves up to the age of 4 months].

In the post-natal period (up to the age of four months), healthy heifer calves of the Bohemian Spotted breed (n = 204) were studied for the levels of total calcium, inorganic phosphorus, and magnesium in the blood plasma. The calves were divided into 17 age groups (n = 12), the age interval between the groups being one week. The highest level of total calcium was found in the calves in the first week after birth (11.77 mg%); this level significantly decreased with higher age of the calves. The minimum was recorded in the fifth week (10.13 mg%). The level of inorganic phosphorus was almost unchanged throughout the period under study, ranging about 9 mg% with insignificant variation. The level of magnesium in the plasma was also fairly stable in the first month of age (2.14--2.29 mg%), a slight increase being observed only from the fifth week on. The comparison of the valves measured in the calves with those obtained in cows indicated that the level of calcium (except the value measured in the fifth week) was higher in the valves than in the cows throughout the experimental period, and that the level of phosphorus was also significantly higher than in the cows throughout the same period. Average values of magnesium in the plasma of the calves were mostly lower than in the plasma of the cows; only in the last third of the experimental period were the magnesium levels very close to, or higher than, the levels in the cows. The dynamics of the development of the cations studied in calf plasma, the Ca/P, Ca/Mg, P/Mg, (Ca+Mg)/p ratios, and the ion product Ca. P reflect the function of these osteotrophic minerals in the process of the growth of skeleton.

Age Factors↗
PubMed1981

Reduction of skin water loss in the newborn. II. Clinical trial of two methods in very low birthweight babies.

Two methods of reducing evaporative water and heat loss in the newborn, the thermal blanket and topical paraffin, were compared in a clinical trial. Forty-four babies weighing less than 1.5 kg, nursed in incubators since birth, were either covered with a plastic bubble blanket or had a paraffin mixture applied to their skin at 6- and 8-hour intervals for the first 2 weeks of life. There was no significant difference between the two groups in terms of mortality, morbidity, weight gain or loss, and temperature control. Two babies in the blanket group were removed from the study because of persistently low body temperatures. Five babies in the paraffin group had minor skin rashes and a further 2 had more extensive rashes which led to their removal from the study. Both methods resulted in good temperature control in babies after the first day of life. In the first 24 hours however, neither method of treatment could prevent subnormal body temperatures in the babies weighing less than 1.0 kg, even though the incubator air temperature was on average more than 1 degree C above the rectal temperature. Other methods are necessary to achieve normal body temperatures in these vulnerable babies.

Bedding and Linens↗
PubMed1999

The association of birth interval, maternal age and season of birth with the fertility of daughters: a retrospective cohort study based on family reconstitutions from nineteenth and early twentieth century Quebec.

In a historical follow-up study, we evaluated the association of the fertility of daughters with five perinatal factors: short (< 15 months) or long (> or = 45 months) preceding birth interval, low (< or = 20 years) or advanced (> or = 40 years) maternal age and season of birth. We used data concerning 2062 women married before the age of 31 and born in the Saguenay region of Quebec, Canada, between 1850 and 1899. Time between the wedding and first birth was used for the estimation of differences in fertility. Using logistic regression and controlling for several potential confounders, we found a slightly increased risk of monthly failure of conception for daughters born after a short but not for those born after a long birth interval (odds ratios [ORs] 1.09 [0.89, 1.33] and 0.87 [0.65, 1.16], respectively, with intervals between 21 and 32 months as the reference category). A slightly increased risk of conceptive failure was also seen for daughters of younger and older mothers (ORs 1.08 [0.89, 1.30] and 1.11 [0.91, 1.35], respectively, compared with maternal age between 24 and 30 years as the reference category). Fertility varied by season of birth (P = 0.02), with summer-born daughters having lowest and winter-born daughters having highest fertility. These results are consistent with the idea that maternal factors before or around birth play a role in the aetiology of reduced fertility. The data, however, do not unequivocally support the hypothesis that gave rise to the present study, namely that ovarian development may be disturbed after conception in conditions with an increased risk of maternal menstrual cycle irregularities.

Adolescent↗