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In most pregnant women, the fertilized egg implants into the uterus between 8 and 10 days after fertilization. Implantation after that time increases the risk of miscarriage. This was the conclusion of a study of 221 women who were trying to get pregnant. Daily urine samples were analyzed for biological markers of fertilization and implantation. Of the 189 women who became pregnant, 84% experienced uterine implantation between 8 and 10 days after fertilization. The rates of miscarriage were 13% in those who implanted on day 9, 26% on day 10, 52% on day 11 and 82% after day 11.

Women born with certain birth defects are more likely to have children with the same birth defect. Researchers in Norway analyzed the rate of birth defects in the children of 8,192 women born with birth defects and 451,241 women born with no birth defects. Only 80% of the women born with birth defects survived to the age of 15, compared to 98% of the other women. Only half the women born with birth defects had children compared to 67% of the other women. Women born with birth defects were about twice as likely to have a child with the same birth defect.

Study Question: Is fecundability associated with miscarriage history and future miscarriage risk?Summary Answer: Prior miscarriage was associated with lower fecundability, and participants with a history of subfertility (time-to-pregnancy (TTP) ≥12 months) were at a higher risk of subsequent miscarriage.What Is Known Already: Although miscarriage and low fecundability share common risk factors, prior studies have reported both lower and higher fecundability after miscarriage.Study Design, Size, Duration: In this study, we examined two related associations: one, between miscarriage history and subsequent fecundability and, two, between fecundability and miscarriage risk in the subsequent pregnancy. The study is based on the Norwegian Mother, Father and Child Cohort Study (MoBa). In addition, the outcome of the pregnancy after the MoBa index pregnancy was obtained by linking information from three national health registries: the Medical Birth Registry of Norway, the Norwegian Patient Registry and the general practice database.Participants/materials, Setting, Methods: We examined the association between number of prior miscarriages and fecundability in 48 537 naturally conceived, planned pregnancies in participants with at least one prior pregnancy. We estimated fecundability ratios (FRs) and 95% CIs using proportional probability regression. We further estimated the relative risk (RR) of miscarriage in the subsequent pregnancy as a function of TTP in the MoBa index pregnancy for 7889 pregnancies using log-binomial regression. Multivariable analyses adjusted for maternal age, pre-pregnancy maternal BMI, smoking status, cycle regularity, income level and highest completed or ongoing education.Main Results and the Role Of Chance: Fecundability decreased as the number of prior miscarriages increased. The adjusted FRs among women with one, two and three or more prior miscarriages were 0.83 (95% CI: 0.80-0.85), 0.79 (95% CI: 0.74-0.83) and 0.74 (95% CI: 0.67-0.82), respectively, compared with women with no prior miscarriages. Compared to women with a TTP of <3 months, the adjusted RR of miscarriage in the subsequent pregnancy was 1.16 (0.99-1.35) with TTP of 3-6 months, 1.18 (0.93-1.49) with TTP of 7-11 months and 1.43 (1.13-1.81) with TTP of 12 or more months.Limitations, Reasons For Caution: Information on TTP and prior miscarriages was obtained retrospectively, and TTP was self-reported. MoBa is a pregnancy cohort, and findings may not be generalizable to all women. We were unable to examine the effect of changing partners between pregnancies, as well as other paternal factors such as seminal parameters. We also did not know what proportion of our participants had changed partners between their prior pregnancies and the index pregnancy. Furthermore, it is likely that many early miscarriages are not recognized.Wider Implications Of the Findings: The association between miscarriage and fecundability may reflect a contribution of occult pregnancy losses to TTP, as well as shared underlying causes for reduced fecundability and miscarriage.Study Funding/competing Interest(s): The study was funded by the Research Council of Norway through its Medical Student Research Program funding scheme (project number 271555/F20), its Centres of Excellence funding scheme (project number 262700) and through the project 'Women's fertility - an essential component of health and well-being' (project number 320656). M.C.M. has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement number 947684). A.J.W. is supported by the Intramural Program of the National Institute of Environmental Health Sciences at the National Institutes of Health, USA. The authors report no competing interests.Trial Registration Number: N/A. [ABSTRACT FROM AUTHOR]

Objective: To assess whether clinical and/or laboratory-confirmed diagnosis of maternal influenza during pregnancy increases the risk of seizures in early childhood.Design: Analysis of prospectively collected registry data for children born between 2009 and 2013 in three high-income countries. We used Cox regression to estimate country-level adjusted HRs (aHRs); fixed-effects meta-analyses were used to pool adjusted estimates.Setting: Population-based.Participants: 1 360 629 children born between 1 January 2009 and 31 December 2013 in Norway, Australia (New South Wales) and Canada (Ontario).Exposure: Clinical and/or laboratory-confirmed diagnosis of maternal influenza infection during pregnancy.Main Outcome Measures: We extracted data on recorded seizure diagnosis in secondary/specialist healthcare between birth and up to 7 years of age; additional analyses were performed for the specific seizure outcomes 'epilepsy' and 'febrile seizures'.Results: Among 1 360 629 children in the study population, 14 280 (1.0%) were exposed to maternal influenza in utero. Exposed children were at increased risk of seizures (aHR 1.17, 95% CI 1.07 to 1.28), and also febrile seizures (aHR 1.20, 95% CI 1.07 to 1.34). There was no strong evidence of an increased risk of epilepsy (aHR 1.07, 95% CI 0.81 to 1.41). Risk estimates for seizures were higher after influenza infection during the second and third trimester than for first trimester.Conclusions: In this large international study, prenatal exposure to influenza infection was associated with increased risk of childhood seizures. [ABSTRACT FROM AUTHOR]

The time of conception for almost all pregnancies appears to be during the six days that precede and include the day of ovulation. Researchers analyzed urine tests, days of intercourse, and pregnancy outcomes in 221 healthy women trying to become pregnant. Of 192 pregnancies that began, 129 resulted in live births. For every conception, intercourse occurred at least once during the six days that ended on the day of ovulation. According to a statistical analysis the probability of conceiving on each of these six days varied from 0.10 on the first day to 0.33 on the day of ovulation. The timing of intercourse did not appear to influence either the probability of live birth or the sex of the baby. Only 6% of the pregnancies were definitely caused by sperm that had been in the woman's reproductive tract for three or more days.

Prenatal exposure to diethylstilbestrol does not appear to affect a man's fertility. Researchers contacted 494 men between the ages of 38 and 41 whose mothers had taken part in a randomized trial of diethylstilbestrol to treat pregnancy complications between 1950 and 1952. A total of 253 men had been exposed to the drug prenatally during the study and 241 had not been exposed. Fifteen percent of those exposed to the drug had a testicular malformation, compared to 5% of those who were not exposed. However, the incidence of infertility was no higher in those exposed than in those not exposed. Men with testicular malformations were no more likely to be infertile than those without such malformations. The rates of pregnancy in the men's female partners were also similar in the two groups.

Objectives. The hypothesis was tested that unfavorable social conditions are associated with poor perinatal survival through direct effects on pregnancy or, more indirectly, through effects on mothers born under such conditions. The occupation of Norway by Nazi Germany was used as a period of social hardship. Methods. Data from Norwegian vital statistics and the Medical Birth Registry were used to describe perinatal mortality during World War II and also a generation later, among babies born to mothers who had themselves been born during the war. Logistic regression was used to identify a possible cohort effect among mothers born in 1940 through 1944 compared with mothers born before or after that period. Results. Harsh conditions in Norway during the occupation increased childhood mortality. However, perinatal mortality declined during that period. Likewise, no adverse effect was seen on the survival of babies born to mothers who had themselves been born during the war (odds ratio = 1.00; 95% confidence interval = 0.96, 1.04). Conclusions. We find no evidence that wartime conditions in Norway impaired perinatal survival, either directly or through an effect on women born during the war. These data underscore how little is known about the ways that social conditions influence perinatal mortality. (Am J Public Health. 1994;84:1463-1467), Extreme social conditions may have an impact on the health and survival of women and through them, infants. The effects may be a result of extended hardship over the life of the mother and/or from events more immediate to the pregnancy and birth. An analysis of the vital statistics and the Medical Birth Registry of Norway reviewed the effects of World War II and the occupation of Norway on the health of women who were children during the war and their babies. While all mortality rates have declined since 1921 in Norway, there was a significant rise in child mortality during the war years. The conditions in occupied Norway were expected to affect the health of the girls growing up then in such a way that the infant mortality rates would be higher when they were having children. This did not occur. It should be noted that extreme malnutrition was not common in Norway, although there was deprivation.

Women whose first child has a birth defect appear to be more likely than other mothers to have a second child with a birth defect. The medical records of 371,933 women in Norway who had given birth to two children were reviewed. A total of 2.5% of the first-born infants and 2.1% of the second-born infants had birth defects. Mothers who delivered babies with birth defects in their first pregnancy were 2.4 times more likely to deliver a second child with birth defects than other mothers. Of women whose first child had a birth defect, those who were living in the same region while pregnant with their second child were 11.6 times more likely to have a child with a similar defect. Most children with birth defects have the same defect as their sibling. The risk of having the same defect appear in a second child is 7.6 times higher for mothers whose first child has a birth defect.