A prospective case-control study of risk factors associated with reduced fetal movements during pregnancy

Background: Studies have shown that women who present with reduced fetal movements (RFM) during pregnancy are at higher risk of adverse pregnancy outcomes. Preventing and reducing adverse outcomes can only be achieved through better detection and management of women with RFM. Pregnancy characteristics of women with RFM vary across studies. Aim: To examine potential risk factors for RFM in pregnancy and to determine any differences in identified risk factors between women who experience RFM and women who do not experience RFM. Methods: Ethical approval was granted by the University and Hospital Research Ethics Committees. A prospective case-control study of all women with a singleton pregnancy, presenting to the emergency department, of a large urban maternity hospital, with a primary complaint of RFM after 24 weeks’ gestation (cases) between 1 January -30 September 2020 were compared with women who did not have RFM during pregnancy (controls). Differences were described as frequencies and percentages and assessed using the Pearson Chi square test as appropriate. A p value < 0.05 was regarded as statistically significant. Logistic regression was used to assess the association of maternal characteristics for developing RFM. Findings: 850 women who presented with RFM were compared with 1743 women who did not present with RFM during the study period. Four risk factors were found to be predictive of RFM in pregnancy: age, BMI, parity and anterior placenta. Women with RFM, were significantly younger (33.8 years versus 34.4 years; p<0.01), more likely to be nulliparous (68% versus 43.8%; p<0.001; OR 2.73 95% CI 2.30-3.24), have a higher mean body mass index (26.57 kg/m2 [5.76] versus 25.89 kg/ m2 [5.10]; p<0.01) and more likely to have an anterior positioned placenta (55.6% versus 50.3%; p=0.01). Ethnicity, smoking, previous obstetric, medical history or complications during pregnancy were not found to be predictive of RFM. Conclusions: Knowledge of maternal characteristics associated with RFM could assist in identifying pregnancies at higher risk of adverse perinatal outcomes and aid decision making regarding need for further investigation when a woman presents with RFM during pregnancy.