Determinants of delayed time-to-pregnancy and recall error among pregnancy planners in Denmark
Radin, Rose Georgia
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The prevalence of infertility, the inability to conceive for 2:12 months, ranges from 4-16% in developed countries. We evaluated determinants of fertility impairment and recall error in time-to-pregnancy (TTP) among Danish pregnancy planners participating in a prospective cohort study. Study 1 examined the associations of active and passive smoking with fecundability-the probability of conception in a menstrual cycle given unprotected sexual intercourse-in 3,773 current, former, and never smokers by estimating fecundability ratios (FR) and 95% confidence intervals (CI). Compared with never smokers, fecundability was reduced among current smokers who smoked 2:10 years (FR=0.85, 95% CI: 0.72, 1.00) and among former smokers who had smoked 2:10 pack- years (FR=0.74, 95% CI: 0.60, 0.92). Among never smokers, the FRs were 1.04 (95% CI: 0.89, 1.21) for passive smoking in early life and 0.92 (95% CI: 0.82, 1.03) for passive smoking in adulthood. Study 2 included 910 women with one previous singleton live birth and examined the association between previous caesarean section (CS) and fecundability. We obtained data on prior delivery and obstetric complications via linkages to national registries. Fecundability was not reduced among women who had an emergency CS for an infant in cephalic presentation (FR=0.99, 95% CI: 0.80, 1.22 relative to spontaneous vaginal delivery). The FR was 0.72 (95% CI: 0.53, 0.97) among women who had a CS for an infant in breech presentation and 0.51 (95% CI: 0.25, 1.02) among women who had an elective CS for an infant in cephalic presentation. Study 3 assessed recall error among 425 women who reported their TTP during the fust trimester of the study pregnancy. Recall error, the difference in retrospective and prospective reports of TTP, ranged from -9 to 3 months, with a mean of -0.11 months (95% CI: -0.25, -0.04). Women with TTP>2 had greater recall error than women with TTP:S2. Incorporating recall error into a quantitative bias analysis of last contraceptive method and fecundability produced similar point estimates but wider confidence intervals, compared with the results from the retrospective reports.
Thesis (Ph.D.)--Boston University