Previous abortion and the risk of neural tube defects: a case-control study.

OBJECTIVE: To further explore the association between abortion history and neural tube defect (NTD) risk and the association of different interpregnancy intervals from prior abortion to current conception on NTD risk. STUDY DESIGN: A matched case-control study was conducted. Cases were 459 women who delivered and gestated babies/fetuses with NTDs in two provinces of China and 459 women with live-born infants without an apparent congenital malformation matched with cases by the same region the same hospital and childbirth in the same year as controls. All of the subjects were investigated by trained interviewers with the same criteria. Conditional logistic regression models were used to calculate odds ratios (ORs) and their 95% CI of abortion history and interpregnancy intervals on NTD risk. RESULTS: Women with abortion history did not have an increased risk for spina bifida and encephalocele. The interpregnancy interval of < 6 months from prior abortion to current conception was significantly associated with anencephaly risk. CONCLUSION: Abortion with an interpregnancy interval of < 6 months from prior abortion to current conception may have an increased risk for anencephaly and should be considered in maternal reproductive health care.