No abstract

The objectives of the current study were to calculate: (1) the expected rates of miscarriage by gestational week; (2) the cumulative risk of miscarriage; and (3) the remaining risk of miscarriage for gestational weeks five through 20, through a systematic review of the literature. We searched MEDLINE for articles published in English through the end of 2009. References of articles were also searched. Four studies were identified to have the three necessary pieces of information for the proposed calculations: (1) gestational age at study entry, (2) pregnancy outcome; and (3) the gestational age at which the pregnancy outcome occurred. Data were extracted from each study and Life Table Analysis Methods were conducted. Weekly miscarriage rates varied in the early gestational weeks with the highest rate documented at >20 miscarriages per 1000 women-weeks at each week of gestation prior to week 13. By week 14, the rate for all studies became relatively comparable and fell below 10 miscarriages per 1000 woman-weeks at risk and fell even lower through week 20. The cumulative risk of miscarriage for weeks 5 through 20 of gestation ranged from 11 miscarriages per 100 women to 22 miscarriages per 100 women (11-22%). Based on data from comparable study populations, a range of background miscarriage rates by week of gestation for weeks 5 through 20, the cumulative risk of miscarriage, and the remaining risk of miscarriage are presented. Wider variation of miscarriage rates and risks occurred early in gestation (<14 weeks).

Objective We assessed the risk of adverse fetal outcomes following exposure to individual immunosuppressive drugs in pregnant women with chronic immune mediated diseases. Methods We used health plan data from Tennessee Medicaid and Kaiser Permanente Northern California and Southern California linked with vital records and medical records. Women with inflammatory arthropathies, systemic lupus erythematosus, and inflammatory bowel disease who filled prescriptions for immunosuppressive treatments during pregnancy were included. Major congenital malformations, fetal deaths, and life-threatening neonatal complications were identified from electronic data and validated with medical record review. Results The cohort included 608 infants, including 437 with exposure during pregnancy (402 first trimester, 35 second and third trimester only) and 171 whose mothers filled prescriptions for immunosuppressives before, but not during, pregnancy. There were 25 pregnancies (4.1% of the cohort) with confirmed major congenital malformations, 10 fetal deaths (1.6%), 23 life-threatening neonatal complications among preterm infants (20.4%), and 10 (2.1%) life-threatening complications among term infants. Compared to the reference group (medication treatment before, but not during, pregnancy), the risk ratios for adverse fetal outcomes associated with immunosuppressive use during pregnancy by exposure category included: methotrexate [risk ratio 1.39 (95% confidence interval 0.43,4.53)], tumor necrosis factor inhibitors [0.98 (0.38,2.55)], hydroxychloroquine [1.33 (0.69,2.55)], and other immunosuppressives [0.98, (0.48,1.98)]. Conclusions We found no evidence of a large increase in risk of adverse fetal outcomes from first trimester exposure to immunosuppressive medications, though confidence intervals for risk ratios were wide. Further studies will be needed as use of these medications increases over time.

I studied whether changing a partner, and thus changing the likelihood of human leukocyte antigen (HLA) sharing between mating partners, affects the risk of preterm delivery in the subsequent pregnancy. I identified a total of 128,239 women who had two consecutive births during 1989-1991 through data linkage of the California birth certificates. Paternal date of birth and names on the records of the two consecutive births were compared to determine whether the same father was reported on both records. Three cohorts of women were formed on the basis of the gestational age of their first delivery: <34, 34-36, and >36 weeks. If parental HLA sharing is associated with preterm delivery, the likelihood of HLA sharing was expected to be in a decreasing order from most likely among a <34-week cohort to least likely among a >36-week cohort. Among women in the <34-week cohort, changing partners resulted in a 33% reduction in the risk of early preterm delivery in the subsequent pregnancy compared with those who did not change partners [95% confidence interval (CI), 0.52-0.88]. In contrast, among women in the >36-week cohort, changing partners led to a 16% increase in the risk of early preterm delivery in the subsequent pregnancy (95% CI = 1.04-1.30). Among women in the 34-36-week cohort, changing partners did not affect the risk of preterm delivery (95% CI = 0.78-1.25). These estimates were adjusted for maternal race/ethnicity, age, educational level, prenatal smoking, prenatal care, parity, and interval from birth to conception of the subsequent pregnancy. The findings from this study suggest that the effect of changing paternity depends on the pregnancy outcome with the previous partner and support the hypothesis that parental HLA sharing may be related to preterm delivery.