Early prenatal exposure to pandemic influenza A (H1N1) infection and child psychomotor development at 6 months - A population-based cohort study.

BACKGROUND: Studies investigating gestational influenza and child neurodevelopment are still scarce, particularly concerning timing of infection in pregnancy. This is the first study to investigate associations between gestational influenza and infant psychomotor development and temperament at 6 months. METHODS: Data from The Norwegian Influenza Pregnancy Cohort, established during the 2009 swine flu pandemic, were utilized. Information on influenza infection, vaccination, maternal health and child health and development is available from questionnaires, national registry data and maternal blood samples drawn at delivery. Maternal influenza A H1N1 pdm09 infection was serologically confirmed. 609 children with complete data were identified. Children of exposed and non-exposed mothers were compared using generalized linear models. RESULTS: Children exposed to influenza during gestational weeks (gw) 0-8 had adjusted general development scores indicating slightly delayed development compared to non-exposed children (0.28 standard deviations (SD) 95% confidence interval (CI): -0. 01; 0.58; p = 0.06). The temperamental scores of children exposed during gw 0-8 were slightly higher (0.31 SD; 95% CI: -0. 03; 0.64; p = 0.07) than non-exposed children indicating a more difficult temperament. In comparison, the developmental scores for children exposed in gw 9-40 were -0.31 SD (95% CI: -0. 65; 0.04; p = 0.09) better than non-exposed children, while the temperamental scores were 0.17 (95% CI: -0. 23; 0.56; p = 0.36) for the same period. CONCLUSION: Modest associations were found between maternal influenza A (H1N1) pdm infection during gestational weeks 0-8 and psychomotor development at 6 months.

Perfluoroalkyl substances during pregnancy and validated preeclampsia among nulliparous women in the Norwegian Mother and Child Cohort Study.

Perfluoroalkyl substances (PFAS) are persistent and ubiquitous environmental contaminants, and human exposure to these substances may be related to preeclampsia, a common pregnancy complication. Previous studies have found serum concentrations of PFAS to be positively associated with pregnancy-induced hypertension and preeclampsia in a population with high levels of exposure to perfluorooctanoate. Whether this association exists among pregnant women with background levels of PFAS exposure is unknown. Using data from the Norwegian Mother and Child Cohort Study conducted by the Norwegian Institute of Public Health, we carried out a study of nulliparous pregnant women enrolled in 2003-2007 (466 cases, 510 noncases) to estimate associations between PFAS concentrations and an independently validated diagnosis of preeclampsia. We measured levels of 9 PFAS in maternal plasma extracted midpregnancy; statistical analyses were restricted to 7 PFAS that were quantifiable in more than 50% of samples. In proportional hazards models adjusted for maternal age, prepregnancy body mass index (weight (kg)/height (m)(2)), educational level, and smoking status, we observed no strongly positive associations between PFAS levels and preeclampsia. We found an inverse association between preeclampsia and the highest quartile of perfluoroundecanoic acid concentration relative to the lowest quartile (hazard ratio = 0.55, 95% confidence interval: 0.38, 0.81). Overall, our findings do not support an increased risk of preeclampsia among nulliparous Norwegian women with background levels of PFAS exposure.

Recurrence risk in hyperemesis gravidarum.

OBJECTIVES: To compare the risk of hyperemesis gravidarum in second pregnancies in women with and without hyperemesis in their first pregnancy, and to determine if this risk changes with changes in paternity or with the interval between deliveries. DESIGN: Cohort study. SETTING: Data from the population-based Medical Birth Registry of Norway, 1967-1998. Sample All women in the registry with records of their first and second singleton delivery, a total of 547,238 women. METHODS: The relative risk of hyperemesis in the second delivery was estimated as odds ratios (ORs) in logistic regression models, controlling for potential confounding factors. MAIN OUTCOME MEASURES: The main outcome measure was the risk of hyperemesis in the second pregnancy according to hyperemesis in the first pregnancy, interval between deliveries and change in paternity. RESULTS: The risk of hyperemesis was 15.2% in the second pregnancy in women with and 0.7% in women without previous hyperemesis [OR=26.4, 95% confidence interval (CI) 24.2, 28.7]. The OR did not change after adjustment for maternal age, change in paternity, period of the first delivery and time interval between deliveries. After a change in paternity, the risk of recurrent hyperemesis was 10.9% compared with 16.0% in women without a change in paternity [adjusted OR (aOR)=0.60, 95% CI 0.39, 0.92]. The risk of hyperemesis in the second pregnancy increased with increasing time interval between deliveries, but only in women with no previous hyperemesis. CONCLUSIONS: The primary finding was the high risk of recurrence observed in women with hyperemesis in the first pregnancy. The risk was reduced by a change in paternity. For women with no previous hyperemesis, a long interval between births slightly increased the risk of hyperemesis in the second pregnancy. Further studies are needed to explore the relative impact of genetic and environmental factors and their possible interactions in hyperemesis gravidarum.

Recurrent risk of anal sphincter laceration among women with vaginal deliveries.

OBJECTIVE: The first aim of this study was to estimate the impact of anal sphincter laceration during the first delivery on the risk of recurrence in the second delivery. The second aim was to estimate the absolute risk of anal sphincter laceration in the second delivery according to the history of anal sphincter laceration and birth weight. METHODS: In this population-based cohort study, the study sample comprised all women included in the Norwegian Medical Birth Registry with 2 consecutive singleton vaginal deliveries during the period 1967-1998 (n = 486,463). The impact of prior anal sphincter laceration on recurrent anal sphincter laceration was estimated as crude and adjusted odds ratios (ORs). RESULTS: Anal sphincter laceration during first delivery increased the risk for a sphincter laceration in the next delivery, (adjusted OR 4.3, 95% confidence interval [CI] 3.8-4.8). Other risk factors were birth weight (adjusted OR 23.6, 95% CI 16.5-33.6, birth weight > 5,000 g versus birth weight < 3,000 grams), use of forceps (adjusted OR 5.1, 95% CI 4.3-6.0), use of vacuum (adjusted OR 1.4, 95% CI 1.1-1.7), and period of delivery (adjusted OR 4.3, 95% CI 3.7-5.0 for 1995-1998 versus 1967-1975). The absolute risks for anal sphincter laceration at second delivery for women with prior laceration were 1.3% (95% CI 0.4-3.2%) for birth weight less than 3,000 g and 23.3% (95% CI 11.8-38.6%) for birth weight more than 5,000 g. CONCLUSION: Only 10% of women with anal sphincter laceration at second delivery had a history of prior laceration. Prior anal sphincter laceration is associated with increased risk of laceration in second delivery, in particular in women who carry children with high birth weight. LEVEL OF EVIDENCE: II-2.