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PubMed2001

Low activity of the ahr gene in the ahr dd C57BL congenic mice does not prevent the depression of birth rates observed as result of cigarette smoke exposure.

The ahr gene product is a ligand-activated transcription factor which regulates the expression of a number of enzymes involved in the metabolism of aryl hydrocarbons and mediates the effects of dioxins on tumour promotion. We have assessed the cigarette smoke induced depression of the reproductive capacities in the ahr dd C57BL congenic mice and its crosses with C57BL ahr bb mice. The in vivo exposure of animals to toxic concentrations of cigarette smoke during the period of pairing and the early pregnancy was shown by us to affect the reproduction. The transmission of the ahr b and ahr d alleles was assessed by genotyping the STR polymorphism at D12Mit2 locus linked with the ahr gene. Following the exposure to cigarette smoke the changes in the reproductive capacity of the studied mice have been assessed in relation to the presence of the ahr d allele by measurements of the changes in the rates of conceptions, abortions, births and the number of newborns per female after pairings differing in ahr gene alleles and in the expected ahr d allele frequencies in the progeny. The results indicates that the low activity ahr d allele may decrease the abortive effects of cigarette smoke exposure, but does not confer resistance to the depression of births rates following this exposure.

Abortion, Spontaneous↗
PubMed1992

Socioeconomic factors affecting first marriage and birth rates by sex and age in the total Japanese population.

The effects of a wide variety of social, economic and demographic factors on age-specific first marriage and live birth rates in 46 Japanese prefectures were analyzed using stepwise regression analysis for 1970 and again for 1975 after classification of those twenty-two factors by factor analysis. The principal results were as follows: (1) high employment (high income) and social mobility caused by industrialization had a strongly positive influence on the first marriage and birth rates for young females, (2) rural and urban residence factors had positive effects on the marriage and birth rates for young males and females, respectively, (3) old age factor had an inverse effect on the marriage rates for both males and females over a wide range of ages, and (4) young age factor promoted the birth rate for young and middle-aged females. The characteristics of the first marriage and live birth rates in Japan were discussed in the light of these findings.

Adolescent↗
PubMed2000

Variation in home-birth rates between midwifery practices in The Netherlands.

OBJECTIVE: To examine the reasons for the variation in home-birth rates between midwifery practices. METHOD: Multi-level analysis of client and midwife associated, case-specific and structural factors in relation to 4420 planned and actual home or hospital births in 42 midwifery practices. FINDINGS: Women's choice of birth location and the occurrence of complications that lead to referral to specialist care before or during labour, were found to be the main determinants of the home-birth rate. Yet, about 64% of the variation between midwifery practices is explained by midwife and practice characteristics. Higher home-birth rates were associated with a positive attitude to home-birth, a critical attitude to hospital birth for non-medical reasons, and good co-operation between midwifery practices and hospital obstetricians. CONCLUSIONS: The proportions of planned hospital birth and of referral to specialist care are the most important predictors of the actual hospital-birth rate of women receiving midwifery care. Both can be influenced by the midwife through a positive attitude to home-birth, a critical approach to non-medical reasons for hospital birth, and good co-operation with specialist obstetricians. It is, therefore, important for midwives to be aware of the influence that their own attitudes may have on the choices their clients make about home or hospital birth.

Adult↗
PubMed1979

The mortality and birth rates of spina bifida during a period of treatment, selection and antenatal screening in Sheffield, 1963-1978.

The birth rates for all neural tube defects and the mortality rates from spina bifida and encephalocele have been obtained for Sheffield children by examining the congenital anomalies register and death certificates during the period from 1963-1978. The introduction of atenatal alpha foetoprotein screening of all pregnant women in 1977 is associated in time with a sharp fall in the birth rate of neural tube defects. The mortality rate for spina bifida with encephalocele rose gradually from 1967 to 1976, apparently unaffected by the introduction of clinical selection prior to surgery in 1971. The antenatal screening of previously affected families (since 1973) did not affect the mortality rate, but screening the total pregnant population since 1977 has been associated with a sharp reduction in the mortality rate. The mortality rate curve for spina bifida with encephalocele is markedly different from the birth rate curve which makes the common practice of inferring birth rates from mortality rates invalid. There was a gradual increase from 1967 to 1978 in the proportion of children born with spina bifida in any given year who died before their second birthday. This increase appears to have been uninfluenced by the introduction of selection or antenatal screening. The changes in mortality rate and survival may be as much due to unknown factors as to changes in medical management.

Amniotic Fluid↗
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↗
PubMed1979

Analysis of multiple birth rates in Japan. 1. Secular trend, maternal age effect, and geographical variation in twinning rates.

Mean twin, triplet, and quadruplet birth rates in Japan from 1951 to 1968 were 6.41, 0.056, and 0.00094 per 1,000, respectively. In 1974 the corresponding figures were 5.83, 0.059, and 0.00329. No quintuplets were born in the former period, but a set was born in the latter year, the rate being 0.47 per million. From 1955 to 1966 the MZ twinning rate increased slightly, but decreased thereafter. This increase was limited to live-born MZ twins, particularly in the higher maternal age groups. The DZ twinning rate declined in the entire period, particularly in higher maternal age groups. This decline appeared to be essentially limited to fetal deaths. Among live births the MZ twinning rate underwent a nearly linear increase with maternal age, whereas the DZ twinning rate attained a mode in the maternal age group 35--39 years. The MZ and the DZ twinning rates among fetal deaths by maternal age had unimodal distributions with modes in maternal age groups 25--29 and 30--34 years, respectively. As to the DZ twinning rate, a geographical cline was noted, with a high rate in the northeast of Japan; the rate was positively correlated with latitude, which also positively correlated with the presence of multiple births among relatives. A negative but nonsignificant correlation was seen between the DZ twinning rate and the proportion of mothers treated with ovulation-inducing hormone. The proportion was higher in mothers of unlike-sexed twins than in those of like-sexed twins and in mothers of triplets than in those of twins. An association between DZ twinning rate and age-specific fertility per married woman is suggested to exist among higher maternal age groups in the northeast part of Japan in earlier years.

Adult↗
PubMed2001

The birth rate of hypospadias in the Turku area in Finland.

Reports based on national registers of congenital malformations have suggested that the birth rate of hypospadias has increased during the last few decades. Register-based information may, however, have pitfalls because of changes in diagnostics, reporting accuracy and registration system. The aim of this study was to determine the current birth rate of hypospadias in Turku University Central Hospital (TUCH) in Finland. This was a prospective study on live-born boys born in TUCH from 1997 to 1999. In the total birth cohort (n=5,798) as well as in a special subcohort group (n=1,505) 0.3% of boys had hypospadias. Only one scrotal hypospadias was found in a boy who had a chromosomal anomaly. Other hypospadias were glandular or coronal. No increase was found in the birth rate of hypospadias when comparing our result with register-based data of boys born in Finland during the years 1970 to 1986 and surgically treated for hypospadias by the age of 8 years. No difference was found either from malformation register-based data concerning the nationwide birth rate of hypospadias during the years 1993 to 1998. Due to differences in national registration systems between countries, prospective studies with equal assessment criteria are needed in order to make reliable international comparisons.

Birth Rate↗
PubMed1995

Caesarean birth rates worldwide. A search for determinants.

High caesarean birth rates are an issue of international public health concern. Determinants of caesarean birth are reviewed in order to formulate strategies to reduce these high rates. A strong independent profession of highly qualified midwives, who care for women with low-risk pregnancies, may contribute to a relatively low caesarean birth rate. Different clinical policies which influence the intervention rate, are discussed for the most frequent reasons to perform caesarean section: dystocia, repeat caesarean birth, breech delivery and foetal distress. The risks and safety of caesarean birth differ from place to place in this world. As the relative safety of the procedure is an important factor contributing to the rise of caesarean birth, the fact that this has only been achieved in some parts of the world should restrict the indications to perform the operation in the best interests of pregnant women.

Birth Rate↗
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↗
PubMed1992

Information dissemination and the cesarean birth rate. The Illinois experience.

A study was initiated to investigate the impact of information dissemination in Illinois upon the projected rise in the cesarean birth rate over the period from 1986 through 1988. The total cesarean birth rate in Illinois had not changed significantly during this period, whereas the rate of vaginal births after cesarean sections (VBAC) increased by 58.4% (p < .001). Information dissemination may have contributed to stemming an increase in the cesarean birth rate in Illinois while promoting VBAC deliveries.

Adolescent↗
PubMed2000

Bacteria in the transfer catheter tip influence the live-birth rate after in vitro fertilization.

OBJECTIVE: To assess the impact of individual bacteria isolated from the vagina and tip of the embryo transfer catheter on live-birth rates. DESIGN: Prospective clinical study. SETTING: Infertility outpatient clinic of a university hospital. PATIENT(S): Ninety-one women undergoing IVF-ET. INTERVENTION(S): Cultures were obtained from the vagina for aerobic and anaerobic bacteria at the time of both sonographic egg retrieval and embryo transfer and from the tip of the embryo transfer catheter. Doxycycline treatment was started after egg retrieval. MAIN OUTCOME MEASURE(S): The live birth of one or more neonates. RESULT(S): Doxycycline had no substantial impact on the recovery of individual vaginal bacteria or on bacterial vaginosis. An increase in live-birth rate was associated with the recovery of hydrogen peroxide-producing Lactobacillus from the vagina (P=0.01) and from the embryo transfer catheter (P=0.01). In contrast, a reduction in live-birth rate was associated with recovery of Streptococcus viridans (S. viridans) from the embryo transfer catheter tip (P=0.04). CONCLUSION(S): In the setting of IVF-ET, prophylactic doxycycline had little effect on vaginal bacteria. Specific bacteria recovered from the embryo transfer catheter appear associated with a detrimental or beneficial effect or with no effect on live-birth rates.

Adult↗
PubMed2004

Cumulative live birth rates after transfer of cryopreserved ICSI embryos.

A cohort follow-up study was designed to assess the efficacy of an intracytoplasmic sperm injection cryopreservation programme through analysis of cumulative live birth rates in successive frozen-thawed cycles in a tertiary referral centre. There were 2013 patients and they underwent 2680 frozen-thawed embryo transfer cycles. The follow-up period was between 1992 and 2001. Only frozen-thawed embryo transfer cycles up to the fourth trial were included. Crude cumulative live birth rates were calculated in five age subgroups, i.e. <30, 30-34, 35-37, 38-39 and >/=40 years old and in surgically or non-surgically retrieved sperm subgroups. Expected cumulative live birth rates were calculated only for the total number of patients. Outcome measure was a live birth occurring after 25 weeks of gestation. Overall, the expected cumulative live birth rate was as high as 26.7% after four cycles while the crude cumulative delivery rate was 10.5%. Multiple cryopreserved embryo transfer cycles increase the chance of a couple to achieve a live birth.

Adult↗
PubMed1984

Determinants of the increasing cesarean birth rate. Ontario data 1979 to 1982.

We analyzed the records of 454,668 births in Ontario in the years 1979 to 1982 and found that the cesarean birth rate increased from 16.5 per hundred deliveries in 1979 to 18.7 in 1982. Cesarean births were classified according to four indications: previous cesarean birth, breech presentation, dystocia, and fetal distress. The increase in the cesarean rate for each indication from 1979 to 1982 was calculated and expressed as a percentage of the total rate increase. Previous cesarean births accounted for 68 per cent of the increase, breech presentation for 14 per cent, dystocia for 4 per cent, and fetal distress for 14 per cent. The impact of previous cesarean births was indicated by an increase in the number of women presenting with this indication--from 5.8 to 7.8 per cent of all deliveries. Although the incidence of breech presentation remained stable, the cesarean birth rate increased from 54.8 to 65 per cent for this indication. There were no marked changes in either the incidence of or cesarean rates for dystocia. The incidence of fetal distress doubled (2.4 to 4.7 per cent of deliveries), but the rate of cesarean births in these cases fell from 50.5 to 32.7 per cent. These findings suggest that physicians may have begun to respond to rising professional and public concern over the increasing cesarean birth rate, but major advances in controlling this rate can be achieved only by addressing the question of vaginal deliveries for some patients who have previously had cesarean section.

Breech Presentation↗