Although the World Health Organization recommends that women wait at least 2 years after a live birth and at least 6 months after a miscarriage or induced abortion before conceiving again to reduce the chances of adverse birth outcomes in the subsequent pregnancy, no recommendation for the optimal interval after stillbirth exists.

The researchers investigated the association between interpregnancy intervals after stillbirth and birth outcomes in the following pregnancy and determined that women who conceive within 1 year of stillbirth are not at an increased risk for another stillbirth, according to study results published in The Lancet.

The interpregnancy interval was defined as the time between the delivery date of the previous pregnancy and the start of the next pregnancy. Interpregnancy intervals were categorized as ≤6 months, 6 to 11 months, 12 to 23 months, 24 to 59 months, and ≥59 months. Birth outcomes in the subsequent pregnancy were defined as stillbirth (fetal death at ≥22 weeks’ gestation), preterm birth (birth before 37 completed weeks of gestation), and small-for-gestational-age birth (<10th percentile for weight at completed gestational age by sex).

A total of 14,452 singleton births were identified in women who had a stillbirth in the previous pregnancy. The median interpregnancy interval after a stillbirth was 9 months compared with 25 months after a live birth. After stillbirth, 9109 (63%) of women conceived again within 12 months and 5393 (37%) conceived within 6 months. Compared with interpregnancy intervals of at least 6 months, intervals <6 months were more common in women age 25 to 34.

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Of the singleton births, 14,224 (98%) were live births, and 228 (2%) were stillbirths; 2532 (18%) were preterm births, and 1284 (9%) were small-for-gestational-age births. Of the 228 stillbirths, 201 (88%) were preterm and 27 (12%) were stillborn at term. No association was found between an interpregnancy interval of ≤6 months, 6 to 11 months, or 12 to 23 months and the risk for subsequent stillbirth compared with an interpregnancy interval of 24 to 59 months. No significant increase in the odds for preterm birth or small-for-gestational-age birth was found for an interpregnancy interval <6 months compared with an interval of 24 to 59 months. These results suggest that women who wish to become pregnant shortly after a stillbirth are not at an increased risk for poor outcomes in the subsequent pregnancy.

“These findings could be used when counselling families that are planning future pregnancies after a stillbirth and provide reassurance to women who wish to become pregnant or unexpectedly become pregnant shortly after a stillbirth,” the investigators concluded.

Reference

Regan AK, Gissler M, Magnus MC, et al. Association between interpregnancy interval and adverse birth outcomes in women with a previous stillbirth: an international cohort study [published online [February 28, 2019]. Lancet. doi:10.1016/S0140-6736