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Comparative Study
. 2015 Dec;25(12):936-41.e1.
doi: 10.1016/j.annepidem.2015.09.001. Epub 2015 Sep 14.

History of Oral Contraceptive Use and Risk of Spontaneous Abortion

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Free PMC article
Comparative Study

History of Oral Contraceptive Use and Risk of Spontaneous Abortion

Kristen A Hahn et al. Ann Epidemiol. .
Free PMC article

Abstract

Purpose: To examine the association between pregravid oral contraceptive (OC) use and spontaneous abortion (SAB).

Methods: In an Internet-based preconception cohort study of 4862 Danish pregnancy planners, we used Cox proportional hazards models to estimate adjusted hazard ratios and 95% confidence intervals (CIs) for the association between OC use and SAB. We controlled for maternal age, physical activity, parity, education, alcohol and caffeine consumption, body mass index, and smoking.

Results: Compared with women who discontinued OCs >1 year before conception, HRs were 0.95 (95% confidence interval (CI) = 0.77-1.17), 0.99 (95% CI = 0.82-1.19), and 0.80 (95% CI = 0.60-1.06) for women who discontinued OCs 7-12, 2-6, and 0-1 months before conception, respectively. Compared with less than 4 years of OC use, HRs for 4-7, 8-11, and 12 years or more of OC use were 1.05 (95% CI = 0.80-1.37), 0.92 (95% CI = 0.71-1.19), and 0.88 (95% CI = 0.65-1.19), respectively. Dose of estrogen and generation of progestin were not materially associated with SAB risk.

Conclusions: We found no evidence that pregravid OC use is associated with an increase in SAB. Use within 1 month of conception was associated with a slightly lower risk of SAB, but this may be due to increased reproductive fitness in women who conceive quickly after discontinuation of OCs.

Keywords: Cohort study; Oral contraceptive; Spontaneous abortion.

Figures

Figure 1
Figure 1
Relationship between recency of oral contraceptive use in months and risk of spontaneous abortion fitted by restricted cubic splines. Adjusted for maternal age, physical activity, parity, vocational training/education, alcohol consumption, caffeine consumption, duration of oral contraceptive use, body mass index, and smoking. 5 knots at 0.5, 3, 6, and 20 months.
Figure 2
Figure 2
Relationship between duration of oral contraceptive use in years and risk of spontaneous abortion fitted by restricted cubic splines. Adjusted for maternal age, physical activity, parity, vocational training/education, alcohol consumption, caffeine consumption, recency of oral contracpetive use, body mass index, and smoking. 4 knots at 3, 6, 10, and 13 years.

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