Prior spontaneous abortion, prior elective termination, interpregnancy interval, and risk of neural tube defects.
A woman with a history of spontaneous abortion in her immediately prior pregnancy may be at increased risk for a pregnancy affected by a neural tube defect (NTD). A short interpregnancy interval may further increase this risk. Using data from a population-based case-control study (1989-1991), the authors investigated NTD risk resulting from a prior spontaneous abortion or elective termination and a short interpregnancy interval. Of 538 interviewed case mothers and 539 interviewed control mothers, 408 case mothers and 433 control mothers reported having a prior pregnancy. Analysis showed a slightly decreased NTD risk among mothers whose immediately prior pregnancy had ended in a spontaneous abortion or elective termination in comparison with a live birth (odds ratio (OR) = 0.82; 95% confidence interval (CI): 0.61, 1.1). This decreased risk was consistent across strata of short or long interpregnancy intervals. Additional analysis revealed an increased NTD risk for mothers with an interpregnancy interval of < or =6 months compared with >12-< or =24 months (OR = 1.5; 95% CI: 0.93, 2.4). This latter risk was greatest among mothers whose immediately prior pregnancy had resulted in a live birth (OR = 2.0; 95% CI: 1.0, 3.8) rather than a spontaneous abortion or elective termination (OR = 0.96; 95% CI: 0.44, 2.1). Adjustment for potential covariates did not substantially alter observed risk estimates.
Todoroff
K
K
California Birth Defects Monitoring Program, March of Dimes Birth Defects Foundation, Emeryville 94608, USA.
Shaw
G M
GM
D000028:Abortion, Induced / Q000009:adverse effects*; D000022:Abortion, Spontaneous / Q000150:complications*; D000328:Adult; D002140:California / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D007231:Infant, Newborn; D009436:Neural Tube Defects / Q000453:epidemiology* / Q000209:etiology; D016017:Odds Ratio; D011247:Pregnancy; D017584:Reproductive History; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors