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UBC Theses and Dissertations

Risk assessment of birth defects in human pregnancy Alwan, Sura


Major birth defects occur in 2% to 3% of liveborn infants and are the leading cause of infant mortality. The cause of most birth defects is unknown. The objectives of this thesis are to (1) assess the risk of having a birth defect in human pregnancy following maternal use of common antidepressant medications and to (2) evaluate the risk of a birth defect or subsequent adverse outcome in relation to restricted fetal growth in early pregnancy. I used data from the National Birth Defects Prevention study, a population-based case-control study of birth defects risk factors in the US to study the rates and patterns of antidepressant medication use around pregnancy and compare the prevalence of common antidepressant medication use among mothers of cases and mothers of controls. I found that selective serotonin reuptake inhibitors (SSRIs) were the most commonly used antidepressants among pregnant women, followed by bupropion, and that the rate of maternal antidepressant use significantly increased over the period between 1998 to 2005. I found that maternal use of SSRIs in early pregnancy was associated with the occurrence of anencephaly, craniosynostosis and omphalocele in the infant, whereas early pregnancy exposure to bupropion was associated with an increased risk for left outflow tract heart defects. I also conducted a retrospective cohort study using ultrasound examination data on singleton pregnancies in women with regular menstrual cycles who had crown-rump length (CRL) measurements at the Ultrasound Unit of British Columbia Women’s Hospital. I found that a first trimester CRL in the 10th centile or less was strongly associated with subsequent spontaneous abortion, delivering through a cesarean section or having an infant with low birth weight or length. The results presented in this thesis indicate that maternal treatment with common antidepressant medications may increase the risk for certain birth defects and that restricted growth of the embryo may adversely affect subsequent pregnancy outcomes.

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