Objective: To investigate if second trimester pregnancy loss (second trimester miscarriage [STM] or termination for medical reasons [TFMR]) was associated with subsequent adverse pregnancy outcomes.
Design: Retrospective cohort study.
Setting: Conducted using the Aberdeen Maternity and Neonatal Databank [AMND] in Aberdeen, United Kingdom.
Population: Women with and without a history of STM or TFMR (between 13 + 0 and 23 + 6 weeks' gestation).
Methods: Logistic and linear regression were used to determine associations between exposed (prior STM or TFMR) and unexposed women (women with prior livebirth).
Main outcome measures: The primary outcome was subsequent spontaneous preterm birth, defined as spontaneous onset of labour and birth between 24 + 0 and 36 + 6 weeks' gestation.
Results: The study included 65 592 women with first and second pregnancies recorded from 1950 to 2017. Women who had a STM in their first pregnancy (n = 935) were at significantly greater risk of spontaneous preterm birth in the next pregnancy (4.3% vs. 1.5%; adjusted Odds Ratio [aOR] 2.55 (95% CI 1.81 to 3.50); p < 0.01). Women with STM in their first pregnancy were two-fold more likely to have a repeat second trimester miscarriage (3.7% vs. 1.1%; aOR 2.25 (95% CI 1.53 to 3.19); p < 0.01). Women who had a first TFMR (n = 177) were significantly more likely to have a repeat TFMR (adjusted OR [aOR] 6.59 (3.4% vs. 0.3%, 95% CI 2.54 to 13.99); p < 0.01). There was no observed increased risk of spontaneous preterm birth after TFMR detected in this sample (aOR 1.06 (95% CI 0.39 to 2.87); p = 0.91) though the sample size was too small to be conclusive.
Conclusions: Women with a history of second trimester pregnancy loss have an increased risk of adverse pregnancy outcomes in a subsequent pregnancy. Consequently, antenatal care surveillance and counselling may need to be increased for women with a prior STM, who are at risk of spontaneous preterm birth and other adverse obstetric outcomes including pre-eclampsia. Women after TFMR can be reassured by our findings; however, larger cohorts are needed to confirm these results.