Time to conception after miscarriage: How long to wait?
EVIDENCE-BASED ANSWER:
An interpregnancy interval (IPI) of < 6 months following miscarriage is associated with an increased live birth rate in subsequent pregnancy, lower risks of preterm birth and subsequent miscarriage, and no difference in rates of stillbirth, pre-eclampsia, and low birth weight infants (strength of recommendation [SOR]: A, well-done meta-analysis). (IPI is defined as the time between the end of one pregnancy and the last menstrual period of a subsequent one.)
A very short IPI (< 3 months), when compared with an IPI of 6 to 18 months, is associated with the lowest rate of subsequent miscarriage (SOR: B, cohort study). However, for women who experience a pregnancy loss at 14 to 19 weeks’ gestation, an IPI < 3 months is associated with an increased risk of miscarriage or birth before 24 weeks’ gestation (SOR: B, cohort study).
Women with a short IPI following miscarriage may be at increased risk for anxiety and depression in the first trimester of the subsequent pregnancy (SOR: B, cohort study).
But a short IPI after second-trimester loss increases risk of miscarriage
By including all miscarriages, the meta-analysis effectively examined IPI after first-trimester loss because first-trimester loss occurs far more frequently than does second-trimester loss.1 A retrospective cohort study of Australian women, not included in the meta-analysis, assessed 4290 patients with a second-trimester pregnancy loss to specifically examine the association between IPI and risk of recurrent pregnancy loss.9
After a pregnancy loss at 14 to 19 weeks, women with an IPI < 3 months, compared with an IPI of 9 to 12 months, had an increased risk of recurrent pregnancy loss (21.9 vs 11.3%; P < .001). Women with an IPI > 9 to 12 months had rates of pregnancy loss similar to an IPI of 3 to 6 months (RR = 1.24; 95% CI, 0.89-1.7) and 6 to 9 months (RR = 1.02; 95% CI, 0.7-1.5). Women who experienced an initial loss at 20 to 23 weeks, for unclear reasons, showed no evidence that the IPI affected the risk of subsequent loss.
Short IPI may be linked to anxiety in first trimester of next pregnancy
A large cohort study of 20,308 pregnant Chinese women, including 1495 with a previous miscarriage, explored the mental health impact of IPI after miscarriage compared with no miscarriage.10 Investigators used the Self-Rating Anxiety Scale to evaluate anxiety and the Center for Epidemiologic Studies Depression Scale to evaluate depression.
Women with an IPI of < 7 months after miscarriage were more likely to experience anxiety symptoms in the subsequent pregnancy than were women with no previous miscarriage (adjusted odds ratio [AOR] = 2.76; 95% CI, 1.4-5.5), whereas women with a history of miscarriage and IPI > 6 months weren’t. Women with IPIs < 7 months and 7 to 12 months, compared with women who had no miscarriage, had an increased risk of depression (AOR = 2.5; 95% CI, 1.4-4.5, and AOR = 2.6; 95% CI, 1.3-5.2, respectively). Women with an IPI > 12 months had no increased risk of depression compared with women with no history of miscarriage.
The odds ratios were adjusted for age, education, BMI, income, and place of residence. The higher rates of depression and anxiety didn’t persist beyond the first trimester of the subsequent pregnancy.
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