ABSTRACT: Women with a history of 1 or 2 miscarriages or terminations of pregnancy have not been considered to be at risk of adverse pregnancy outcomes in subsequent pregnancies. However, few studies have examined the association between previous pregnancy loss and adverse pregnancy outcomes in subsequent pregnancies; results in the available studies are mixed. It has been suggested that previous use of cervical dilatation and curettage (D&C) for management of first-trimester miscarriage or termination may adversely affect outcomes in subsequent pregnancies.
The aim of this prospective cohort study was to determine whether women with a previous miscarriage or termination of pregnancy are at increased risk of spontaneous preterm birth and to determine whether any increased risk is associated with previous use of cervical D&C. Prospective data were obtained for 5575 healthy nulliparous women with singleton pregnancies who were enrolled from 2004 to 2011 in the Screening for Pregnancy Endpoints (SCOPE) study. The primary study outcome was spontaneous preterm birth (spontaneous onset of preterm labor or preterm premature rupture of membranes resulting in preterm birth at less than 37 weeks’ gestation). Secondary outcomes examined included preterm premature rupture of membrane, small for gestational age, birth weight, placental abruption, and preeclampsia. Comparison groups were women with previous pregnancy loss (miscarriage or termination) and women with no previous pregnancy loss (control).
Among the 5575 women in the study, 4331 (78%) had no previous pregnancy loss, 974 (17.5%) had 1 early previous pregnancy loss, 249 (4.5%) had 2, and 21 (0.5%) had 3 or 4 losses. A single pregnancy loss was not associated with a significant increase in adverse pregnancy outcomes, whereas 2 to 4 previous losses had an increased risk of spontaneous preterm birth (adjusted odds ratio [aOR], 2.12; 95% confidence interval [CI], 1.55–2.90) and/or placental abruption (aOR, 2.30; 95% CI, 1.36–3.89) compared with no previous pregnancy loss. The use of cervical D&C to manage a single previous miscarriage or termination of pregnancy was associated with an increased risk of spontaneous preterm birth (aOR,1.64; 95% CI, 1.08–2.50; 6% absolute risk and aOR, 1.83; 95% CI, 1.35–2.48; 7% absolute risk, respectively) compared with no previous pregnancy loss. In contrast, use of a nonsurgical method for management of a single previous miscarriage or termination did not increase the risk of adverse outcomes in a subsequent pregnancy (aOR, 0.86 [95% CI, 0.38–1.94; 3.4% absolute risk]; and aOR, 0.87 [95% CI, 0.69–1.12; 3.8% absolute risk], respectively).
These findings indicate that a single pregnancy loss managed by cervical D&C is associated with an increased risk of spontaneous preterm birth and/or placental abruption. In contrast, a single pregnancy loss managed nonsurgically does not increase the risk, but 2 to 4 losses are associated with increased risk. Further prospective studies are needed to confirm these data and to determine whether nonsurgical management in this population should be preferable to surgical treatment.