Analysis of the causes and influencing factors of fetal loss in advanced maternal age: a nested case-control study

Background The risk of fetal loss is higher among ≥35-year-olds than younger women. The present study aimed to explore the causes and factors influencing fetal loss in advanced maternal age (AMA). Methods AMA women with singleton fetuses (< 14 gestational weeks) who underwent their first prenatal examination in the Obstetrics Department of Fujian Maternity and Child Health Hospital from December 2018 to June 2020 were included in this cohort study. Those who terminated the pregnancy before 14 gestational weeks were excluded. A baseline survey was conducted, and follow-up was carried out until the termination of the pregnancy. Clinical data were extracted to analyse the causes of fetal loss among them. In the nested case-control study, the AMA women with fetal loss were enrolled as the case group, and women without fetal loss in the same period were enrolled as the control group, in a 1:2 ratio matched by age and gestational weeks. Logistic regression models were used to analyse the factors influencing fetal loss. Results A total of 239 women with fetal loss and 478 controls were enrolled. The causes of fetal loss were most often fetal factors, followed by maternal factors, umbilical cord factors, and placental factors. Multivariate logistic regression analysis indicated that junior high school education and below (adjusted odds ratio (aOR) = 5.13, 95% confidence interval (CI): 2.19–12.02), senior high school education (aOR = 4.91, 95% CI: 2.09–11.54), residence in a rural area (aOR = 2.85, 95% CI: 1.92–4.25), unemployment (aOR = 1.81, 95% CI: 1.20–2.71), spontaneous abortion history (aOR = 1.88, 95% CI: 1.26–2.80), preterm birth history (aOR = 11.08, 95% CI: 2.90–42.26), hypertensive disorders of pregnancy (aOR = 7.20, 95% CI: 2.24–23.12), and preterm premature rupture of membranes (aOR = 4.12, 95% CI: 1.53–11.11) were risk factors for fetal loss. Conclusions Low educational level, unemployment, abnormal pregnancy/labor history, and pregnancy complications were correlated with the incidence of fetal loss in AMA. Thus, early identification as well as a targeted intervention, should be conducted.