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PubMed2004

Vaginal bleeding during pregnancy and preterm birth.

This study investigated the relation between self-reported vaginal bleeding during pregnancy and preterm birth in a prospective cohort of 2,829 pregnant women enrolled from prenatal clinics between 1995 and 2000 in central North Carolina. The overall association between vaginal bleeding and preterm birth was modest (risk ratio (RR) = 1.3, 95% confidence interval (CI): 1.1, 1.6). Bleeding in the first trimester only was associated with earlier preterm birth (< or =34 weeks' gestation) (RR = 1.6, 95% CI: 1.1, 2.4) and preterm birth due to preterm premature rupture of the membranes (PPROM) (RR = 1.9, 95% CI: 1.1, 3.3). Bleeding in both trimesters was associated with preterm birth due to preterm labor (RR = 3.6, 95% CI: 1.9, 6.8). Bleeding of multiple episodes, on multiple days, and with more total blood loss was associated with an approximate twofold increased risk of earlier preterm birth, PPROM, and preterm labor. In contrast, bleeding in the second trimester only, of a single episode, on a single day, and with less total blood loss was not associated with any category of preterm birth. Vaginal bleeding was not associated with preterm birth among African Amercians (RR = 1.2, 95% CI: 0.9, 1.7). This study indicates that more intense but not less intense bleeding is associated with earlier preterm birth and spontaneous preterm birth presenting as PPROM or preterm labor, and it suggests that bleeding is less predictive of preterm birth among African-American compared with White women.

Adult↗
PubMed2002

Crossover trial of analgesic efficacy of glucose and pacifier in very preterm neonates during subcutaneous injections.

OBJECTIVE: Very preterm newborns undergo multiple invasive procedures. Nonpharmacological interventions are valuable alternatives for pain relief during minor procedures in neonates. Oral sucrose analgesia has been widely studied in term and preterm neonates during painful procedures. The analgesic effect of oral glucose in very preterm infants has not yet been reported. The objectives of this study were to assess the analgesic effect of orally administered glucose and to determine the synergetic analgesic effect of glucose and pacifiers during subcutaneous injections in very preterm neonates using a validated behavioral acute pain rating scale. DESIGN: Two crossover trials. SETTING: One neonatal intensive care unit in a community-based general hospital. METHODS: A prospective study was conducted in 40 very preterm neonates. Each infant received 2 treatments in a crossover manner during 2 consecutive subcutaneous injections of erythropoietin. The first trial (25 infants) was intended to compare oral 30% glucose (0.3 mL) versus placebo (0.3 mL of sterile water); the second trial (15 infants) compared oral 30% glucose (0.3 mL) versus oral 30% glucose (0.3 mL) followed by sucking a pacifier. The primary outcome measure was the evaluation of pain induced by a subcutaneous injection of erythropoietin, using Douleur Aiguë Nouveau-né scale (0 no pain, 10 maximum pain). RESULTS: Twenty-four infants completed the study in the first trial and 15 in the second one. Mean (95% confidence interval [CI]) gestational age, birth weight, postnatal age, and weight at inclusion for neonates in the first and second trial were, respectively, 28.1 (95% CI: 27.3-29.0) and 29.1 (95% CI: 27.8-30.4) weeks, 1036 (95% CI: 944-1128) and 995 (95% CI: 848-1141) g, 26.4 (95% CI: 22.4-30.3) and 26 (95% CI: 22.0-29.9) days, and 1234 (95% CI: 1120-1348) and 1209 (95% CI: 1059-1359) g. In the first trial, median (interquartile) pain scores for placebo and 30% glucose, respectively, were 7 (2.5-9.75) and 4.5 (1-6). In the second trial, median (interquartile) pain scores for 30% glucose and for 30% glucose plus pacifier, respectively, were 4 (2-7) and 4 (1-6). CONCLUSIONS: A small dose of 0.3 mL of 30% oral glucose has an analgesic effect in very preterm neonates during subcutaneous injections. This effect is clinically evident because it can be detected by a behavioral pain rating scale. The synergetic analgesic effect of glucose plus sucking a pacifier is less obvious in very preterm neonates as opposed to what other studies have showed in full-term infants.

Administration, Oral↗
PubMed1982

[Population biology of northern Germany. 3. Secular changes in the seasonal variation of birth rates in Bremen (from 1826 to 1979)].

The question, whether the seasonal variation of the birth frequencies are changing with the increase of birthcontrol practice in the population is subject of the present study. The changes of the relevant demographic parameters in this context are discussed first. The study is based on the official monthly records of live- and stillbirths from 1826 to 1979 in Land Bremen (an urban district of northern Germany). For analysis, the material is standardized to equal month length. Trend effects were eliminated using the mean curve. To eliminate stochastic effects, the material is summarized using intervals formed analog to the changes in the birth rate. The means of these intervals illustrate two typical figures; the first is characteristic for the period prior to 1905, the second is characteristic for the years following (excluding the periods from 1915 to 1922 and from 1973 to 1978). The transition of these figures occurred at the change of the century. It is regarded in context with the beginning reduction of birth rate at this time. Whereas for the 19th Century, the seasonal changes, particularly from winter to spring, are regarded as a main cause of physiologic adaptation followed by stimulation of the gonadal gland, "sociologic factors" are taken into account for the seasonality of the birth rates in the 20th Century.

Birth Rate↗
PubMed1990

Polymorphonuclear leucocyte and natural killer cell functions in mature and premature newborns.

In this study the phagocytic and natural killer cell (NK) functions in 17 premature and 30 mature newborns are compared. The ability of polymorphonuclear phagocytes (PMNs) to ingest, digest and lyse (antibody-dependent cell-mediated cytotoxicity, ADCC) opsonized sheep red blood cells and NK activity were tested. Examinations were performed in cord and venous blood within 6 h or 3-4 days after delivery. Results of examinations were compared with normal values for the group of healthy 4- to 15-year-old children. To assess the influence of the newborn's maturity and age on the tested PMNs and NK functions, the following comparisons were made. (1) Cord vs. peripheral venous blood: only ADCC was higher in peripheral than in cord blood. (2) Mature newborn cells obtained either 6 h or 3-4 days after delivery: ingestion and ADCC were lower and NK activity was higher 3-4 days after delivery. (3) Premature vs. mature newborn cells tested 3-4 days after delivery: ingestion and ADCC were higher while NK activity was lower in premature newborns. (4) Premature newborns tested at 3-4 days vs. mature newborns tested within 6 h after birth: ingestion was lower in the prematures while digestion, ADCC and NK activity were similar. (5) Cells from all newborns tested vs. those of healthy older children: results depend on the interval after birth when newborns were tested. Thus, within the first 6 h after delivery, mature newborns had higher ingestion and ADCC capacity but lower digestion and NK activity. Later, 3-4 days after birth, ingestion, ADCC and NK activity were lower in mature newborns. In the prematures at that interval NK activity was lower. (6) There was a positive correlation between gestational age and NK activity of newborns.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1991

Risk factors for gallstone disease requiring surgery.

Risk factors for cholelithiasis were investigated in a case-control study conducted in northern Italy on 195 incident cases of gallstone disease requiring surgery (119 females, 76 males) and 1122 controls in hospital for acute, non-digestive tract, non-neoplastic conditions. There was no consistent association with socio-demographic indicators, such as marital status, education and social class nor with smoking and coffee consumption. The relative risk of cholelithiasis decreased with increasing alcohol consumption: compared with non-drinkers, the odds ratio (OR) was 0.8 for one to three drinks per day and 0.5 for over three. A direct association was observed with measures of body weight: relative to leaner individuals, the multivariate ORs were 1.2, 2.1 and 2.4 for subsequent levels of body mass. These trends in risk were statistically significant, consistent in the two sexes, and not apparently modified by adjustment for major identified potential confounding factors. History of hepatitis and liver cirrhosis were reported more frequently by cases, but it is difficult to assess the role of recall bias on these risk factors. No association was found with diabetes, thyroid disease and several digestive tract disorders. For females, no consistent pattern of risk was observed up to four births, but women with five or more births had an OR of 2.9 (95% confidence interval (Cl) = 1.1-7.3). The risk decreased with increasing age at first and last birth, both trends being statistically significant. Overweight and alcohol consumption were the most important risk and protective factors respectively for cholelithiasis requiring surgical intervention in this population.

Adult↗
PubMed1987

Birth control regulations, Fifth People's Conference, 17 May 1986.

These regulations authorize the following exceptions to the one child per couple policy for urban couples: a couple may have a second child when a) the first child is deformed with a non-hereditary disease that prevents the child from growing up to be an able-bodied worker; b) when one spouse of a remarried couple has had only one child and the other spouse has had none, or when both have had a child, but the children have been placed by court order in the custody of the ex-spouses; c) when the wife becomes pregnant and the couple has already adopted a child because either one or both spouses was medically determined to be sterile; d) when both spouses are single children; and e) when either or both of the spouses have worked in a mine or under water continuously for more than five years. For rural couples, the regulations described in a) to d) above are applicable. In addition, a couple may have a second child if their first child is a girl. The interval between the birth of the two children must be no less than four years. Ethnic minority couples living in minority regions are allowed to have two children, and in special circumstances three children. Having a fourth child is strictly forbidden.

Asia↗
PubMed2006

The effects of birth interval on the birthweights of consecutive, same-sex term siblings.

OBJECTIVE: To investigate the effect of birth interval on the relationship between the birthweights of successive siblings. METHODS: The records of women who had delivered two consecutive, same-sex, live, singletons babies (1983 through 1997) in a private hospital were analysed. The intervals between the birth dates of the siblings were calculated. The first of the siblings was coded Set A and the second, Set B. The ratios of the birthweights (Set B/Set A) were calculated. Comparison of findings was made between various ranges of birth interval. RESULTS: The birth interval band 24-29 months was associated with the highest mean birthweight for Set B babies and the highest birthweight ratio (p=0.016). Set A babies weighing less than 3000 g were most likely to be outweighed by their Set B siblings (p=0.000001). CONCLUSION: Birth intervals of 24 to 29 months and small size of Set A babies were associated with most significant advantages in birthweight for Set B siblings.

Birth Intervals↗
PubMed1987

Reproductive history and breast cancer in a population of high fertility, Costa Rica, 1984-85.

The relationship between breast cancer and women's reproductive history in Costa Rica was analyzed using logistic regression methods on data from 171 breast cancer cases and 826 population-based controls aged 25-58 years. The risk of breast cancer in nulliparous women under age 45 was 3 times that for parous women in the same age group. Women over 44 years of age with a parity greater than 4 had a risk of breast cancer of 0.3 compared to women of the same age but with a parity of 1-4. Neither breast-feeding nor birth interval showed an overall association with breast cancer independent of parity. Women with early age at first birth had a lower relative risk of breast cancer than women aged 20-24 at first birth, but only in two subgroups--women aged 45 and over and women with parity 1-4. Women without a completed pregnancy in the last 20 years had an elevated relative risk. However, results are not conclusive because some information is probably distorted by recall errors. Declines in fertility rates in the 1960s and 1970s may result in an increase of 30% in breast cancer incidence in Costa Rica between 1980 and the year 2000, according to the relative risks found in this study. In contrast, the effect of childlessness will probably not produce significant changes in national breast cancer trends.

Adult↗
PubMed2001

Season of birth and reproductive performance: an analysis of family reconstitutions of 800 women born in The Netherlands at the end of the 19th century.

BACKGROUND: Several studies have reported associations between season of birth and reproductive characteristics such as menarcheal age, fecundability, and twinning, but the results are inconsistent with respect to the location of high- and low-risk seasons. To assess whether this disagreement could be due to the use of populations from different geographic areas and time frames instead of different etiologic pathways, we investigated the season-of-birth dependency of a variety of reproductive outcomes within one time- and area-limited population. METHODS: In a historic follow-up study, the reconstituted families of 800 women born between 1873 and 1887 in or near Rotterdam, The Netherlands, were used to determine eight types of reproductive outcome: childlessness, interval to first pregnancy, pregnancy interval, stillbirth, neonatal death, postneonatal death, multiple birth, and gender of offspring. The relation of these outcomes with season of birth was modeled using cosinor functions with periods of 1 year or a half year. Data were analyzed by use of logistic regression or general estimation equations (GEE), dependent on whether outcomes could occur more than once per woman. RESULTS: Peaks in the model-based risks of reproductive failure were found within two small temporal ranges, January 1 to February 11 and July 1 to August 11 for all outcomes except gender. The picture did not change after controlling for known and possible risk factors, including age, offspring's birth cohort, and some social variables. CONCLUSIONS: This study reconfirms the idea that seasonal factors around conception or birth influence later reproductive characteristics. Observing the consistency of the location of high-risk seasons across a variety of outcomes, the explanation of season-of-birth dependency of different reproductive outcomes need not involve multiple etiological pathways.

Female↗
PubMed1994

Pregnancy and birth rates of live infants after in vitro fertilization in women with an without previous in vitro fertilization pregnancies: a study of eight thousand cycles at one center.

OBJECTIVE: Our aim was to compare the cumulative conception and live-birth rates after in vitro fertilization in women undergoing their first course of in vitro fertilization treatment with those in women undergoing their second course of treatment, having previously achieved an in vitro fertilization pregnancy. This study occurred in a tertiary referral-assisted conception unit. STUDY DESIGN: The cumulative conception rates obtained by life-table analysis in 4115 women having their first course of in vitro fertilization therapy (7327 treatment cycles leading to 1123 pregnancies) were compared by means of the log-rank test with those of 331 women in their second course of treatment, having previously achieved an in vitro fertilization pregnancy (561 treatment cycles leading to 138 second in vitro fertilization pregnancies). Similarly, the cumulative live birth rates of 3824 women in their first course of treatment (7136 treatment cycles leading to 732 live births) were compared with those of 105 women in their second course of treatment, having previously achieved an in vitro fertilization live birth (205 treatment cycles leading to 33 second in vitro fertilization live births). RESULTS: The cumulative conception rates and cumulative live birth rates were significantly higher in women having their second course of in vitro fertilization treatment than in those having their first course (cumulative conception rate: p = 0.0001; cumulative live birth rate, p = 0.007). After five cycles of in vitro fertilization, the cumulative conception rates and cumulative live birth rates were 49.8% (95% confidence interval, 46.3% to 53.5%) and 39.0% (95% confidence interval, 35.4% to 42.9%), respectively, in those having their first course of treatment compared with 69.9% (95% confidence interval, 57.6% to 81.3%) and 68.6% (95% confidence interval, 46.1% to 88.5%), respectively, in those having their second course. The estimated median numbers of cycles taken to achieve a pregnancy and live birth (assuming all women could potentially undergo the same number of cycles) were six and eight, respectively, in the first course of treatment compared with only three and five in the second course. CONCLUSION: Women who have achieved a previous in vitro fertilization pregnancy have significantly higher cumulative conception rate and cumulative live birth rates compared with those of women having their first course of treatment.

Adult↗
PubMed1999

Determinants of protogenetic interval in a west Mediterranean rural population: La Alpujarra (southeast Spain).

This paper analyzes the protogenetic interval determinants and the influence on family size. The data came from La Alpujarra (Southeast Spain), consisting on a sample of 847 families marrying through-out the first half of the present century. The marital fertility includes 85% deliveries, 5% premarital births and the remaining 10% premarital conceptions. The protogenetic interval was clearly associated with the reproductive success since family size was nearly one child greater for short intervals (= < 16 months). The protogenetic interval largely depends on the occurrence of miscarriages preceding the first liveborn delivery as well as on maternal age. Consanguineous couples show slightly shorter intervals. A temporal decrease of protogenetic intervals was observed.

Birth Intervals↗
PubMed1987

Breast cancer risk associated with proliferative disease, age at first birth, and a family history of breast cancer.

The authors reevaluated 10,542 consecutive breast biopsies of women who presented at three Nashville hospitals. Median follow-up was 17 years for 3,398 women (84.4% of patients originally selected for follow-up). Breast cancer relative risks associated with no proliferative disease, proliferative disease without atypia, and atypical hyperplasia were 0.80, 1.4, and 4.0 times that for women from the Cancer in Connecticut data base, respectively (adjusted for age at biopsy, year of biopsy, and length of follow-up). Nulliparous women were at increased risk of breast cancer (relative risk = 1.6; 95% confidence interval (CI) = 1.1-2.2). Women who gave birth to their first child before age 21 years had a relative risk of 0.80, with higher cancer risks associated with later age at first birth. The effect of age at first birth on cancer risk followed a similar pattern within the no proliferative disease, proliferative disease without atypia, and atypical hyperplasia groups. Nulliparous women with atypical hyperplasia had a relative risk of 4.9 (95% CI = 2.7-8.9), while women with no proliferative disease who gave birth before age 21 years had a relative risk of 0.50 (95% CI = 0.19-1.3). Nulliparous women with a family history of breast cancer had a relative risk of 2.7 (95% CI = 1.4-5.2). Women with a family history who first gave birth by age 20, between ages 21 and 29, and after age 30 years had relative risks of 0.53, 2.1, and 4.0, respectively (95% CI = 0.08-3.8, 1.1-3.9, and 1.8-9.6, respectively). Breast size had no effect on cancer risk in women without proliferative disease. However, in women with proliferative disease, small, medium, and large breasts were associated with relative risks of 1.2, 1.4, and 2.1, respectively.

Adult↗
PubMed2004

Risk of birth defects associated with nelfinavir exposure during pregnancy.

OBJECTIVE: The objective of this study was to examine the human teratogenic risk of the protease inhibitor, nelfinavir mesylate, used to treat human immunodeficiency virus. METHODS: This study used a subset of data from the Antiretroviral Pregnancy Registry, which was designed to monitor prenatal exposures to antiretroviral therapy and detect a potential increase in the risk of birth defects. The registry uses a prospective exposure-registration cohort design. All records of pregnant women exposed to nelfinavir, used alone or in combination, were extracted and analyzed. The prevalence of birth defects was compared with the Centers for Disease Control and Prevention's (CDC) population-based surveillance system. RESULTS: Through July 2002, the registry had monitored 915 live births exposed to nelfinavir. Among 301 first-trimester exposures, there were 9 birth defects, for a prevalence of 3% (95% confidence interval 1.4, 5.6). This rate is not significantly different from the CDC's system, which had a prevalence of 3.1 per 100 live births (95% confidence interval 3.1, 3.2; P =.99). There was no consistent pattern among reported birth defects. CONCLUSION: Adequate numbers of first-trimester exposures to nelfinavir have been monitored to detect a 2-fold increase in the prevalence of overall birth defects. No such increases have been detected when compared with the CDC rate. However, the numbers are not sufficient to detect any increased rate of specific defects. Although nelfinavir should only be used in pregnancy if the benefits outweigh the potential risks, the findings from this study should provide some assurance. LEVEL OF EVIDENCE: III

Abnormalities, Drug-Induced↗
PubMed2004

16S ribosomal DNA-directed PCR primers for ruminal methanogens and identification of methanogens colonising young lambs.

The population densities and identities of methanogens colonising new-born lambs in a grazing flock were determined from rumen samples collected at regular intervals after birth. Methanogen colonisation was found at the first sampling (1-3 days after birth) and population densities reached around 10(4) methanogens per gram at 1 week of age. Population densities increased in an exponential manner to a maximum of 10(8)-10(9) per gram at 3 weeks of age. To identify methanogens, PCR primers specific for each of the Archaea; a grouping of the orders Methanomicrobiales, Methanosarcinales and Methanococcales; the order Methanobacteriales; the order Methanococcales; the order Methanosarcinales; the genus Methanobacterium; and the genus Methanobrevibacter were designed. Primer-pair specificities were confirmed in tests with target and non-target micro-organisms. PCR analysis of DNA extracts revealed that all the detectable ruminal methanogens belonged to the order Methanobacteriales, with no methanogens belonging to the Methanomicrobiales, the Methanosarcinales, or the Methanococcales being detected. In 3 lambs, the initial colonising methanogens were Methanobrevibacter spp. and in 2 lambs were a mixture of Methanobrevibacter and Methanobacterium spp. In the latter case, the initial colonising Methanobacterium spp. subsequently disappeared and were not detectable 12-19 days after birth. Seven weeks after birth, lambs contained only Methanobrevibacter spp. This study, the first to provide information on the identities of methanogens colonising pre-ruminants, suggests that the predominant methanogens found in the mature rumen establish very soon after birth and well before a functioning rumen develops.

Journal Article↗
PubMed2000

No association of the 5' promoter region polymorphism of CYP17 with breast cancer risk in Japan.

To examine the association between breast cancer risk and a T-to-C substitution polymorphism at the 5' promoter region of CYP17, a case-control study was conducted at Aichi Cancer Center Hospital in Japan. Subjects were 144 histologically confirmed breast cancer patients diagnosed in the past 4 years and 166 hospital controls without cancer. Allele frequency among controls was 44.9% (95% confidence interval; 39.5 - 50.2) for C allele. Odds ratio (OR) of the polymorphism relative to TT-genotype was 0.97 (0.58 - 1.64) for TC-genotype and 0.81 (0.39 - 1.68) for CC-genotype. Subgroup analyses revealed that the OR was not statistically significant for the subgroups stratified by interval after diagnosis, age at menarche, age at first birth, menopausal status, body mass index, and mother / sisters' history of breast cancer. Consistent with previous studies conducted in other countries, the 5' promoter region polymorphism of CYP17 affected breast cancer risk of Japanese women to a limited extent. Although this is not a large-scale case-control study with population controls, these findings provide enough information to discourage further studies on the association between this polymorphism and breast cancer risk in Japan at large, and suggest that this polymorphism is useless for breast cancer risk estimation.

Adult↗
PubMed2002

Does a traumatic birth experience have an impact on future reproduction?

OBJECTIVE: To investigate whether women's experiences of their first birth affects future reproduction. DESIGN: Prospective cohort study. SETTING: South Hospital, Stockholm, Sweden. POPULATION: Six hundred and seventeen women who gave birth to their first child 1989-1992. METHODS: A global measure of women's experiences of their first birth, assessed two months postpartum, was available from a birth centre trial, together with information on a range of background variables. This information was linked to the Swedish Medical Birth Register, which included information on the number of subsequent births during the following 8-10 years. MAIN OUTCOME MEASURES: Number of births (0 or > or =1) following the first birth. RESULTS: Women with a negative experience of their first birth had fewer subsequent children and a longer interval to the second baby (RR 1.7, 95% CI 1.3-2.3). Being 35 years and older (RR 2.6, 95% CI 1.6-3.7), or single (RR 2.6, 95% CI 1.7-3.9) was also associated with subsequent infertility. CONCLUSION: A negative birth experience was associated with subsequent infertility, and women's experiences should therefore be considered seriously in the provision of maternity care.

Adult↗
PubMed1977

Effect of potassium isobutyrate on absorption of immunoglobulins from colostrum by calves.

Calves received either colostrum with 2.83 meq potassium isobutyrate per gram of gamma-globulin or colostrum with distilled water within 1 h after birth. Blood samples were taken at intervals during the first 72 h for determination of concentrations of gamma-globulin, immunoglobulin IgG and IgM. Calves fed colostrum with distilled water attained higher concentrations in serum of total gamma-globulin, immunolgobulin IgG and IgM. Holstein calves were more efficient than Ayrshire calves in absorbing total gamma-globulin, but differences between breeds were not significant for specific immunoglobulins. Efficiency of gamma-globulin absorption within 24 h was 35.7% for control calves and 24.7% for calves fed colostrum plus potassium isobutyrate. Potassium isobutyrate had a depressing effect on absorption of immunoglobulins by calves.

Animals↗
PubMed2006

Determinants of perinatal mortality and serious neonatal morbidity in the second twin.

OBJECTIVE: To identify potential determinants of perinatal mortality and neonatal morbidity among second twins relative to first twins. METHODS: A retrospective cohort design was used to study twin deliveries in Nova Scotia from 1988 to 2002. Monoamniotic or conjoined twins and twin pairs with major congenital anomaly or antepartum fetal death of either twin were excluded. The primary outcome was a composite measure of perinatal mortality and neonatal morbidity, including birth asphyxia, respiratory distress, neonatal trauma, and infection. Risk of adverse outcome of second twins relative to first-born co-twins was determined by matched-pair analysis. RESULTS: Of 1,542 twin pairs, the second twin was at greater risk of composite adverse outcome (relative risk [RR] 1.62, 95% confidence interval [CI] 1.38-1.9) than the first twin. This excess risk was evident independent of presentation, chorionicity, or infant sex but was associated with planned vaginal delivery, birth weight discordance, and prolonged interdelivery interval. Term second twins were less likely to suffer excess morbidity with elective cesarean (RR 1.0, 95% CI 0.14-7.10) than with planned vaginal delivery (RR 3.0, 95% CI 1.47-6.11). The major contributors to neonatal morbidity in the second twin were birth asphyxia at 37 weeks or later and respiratory distress syndrome at less than 37 weeks. CONCLUSION: The second twin is at greater risk of adverse perinatal outcome than the first twin, independent of presentation, chorionicity, or infant sex. Planned vaginal delivery, birth weight discordance, and prolonged interdelivery interval increase this infant risk. Elective cesarean delivery at term may improve perinatal outcome for the second twin. However, the number of cesarean births required to prevent one case of composite adverse outcome, assuming causality, was 33.

Adult↗