Fetal movements are related to maternal characteristics: a prospective ultrasound study.

BACKGROUND

Fetal movements are important indicators of well-being that are associated with stillbirth. Yet neither a universal definition nor gold standard exists for what constitutes normal or abnormal. Current monitoring methods such as maternal perception lack diagnostic accuracy, while ultrasound provides detailed assessment in real time that is not practical outside the clinic setting. Maternal perception remains the primary method of fetal movements detection in clinical practice.

OBJECTIVES

To assess normal fetal movements patterns using real-time ultrasound and maternal perception and relating these to key pregnancy parameters. To investigate how maternal perception is predictive for ultrasound identified movements.

STUDY

DESIGN

Prospective observational study in an inner-city maternity hospital in the United Kingdom, enrolling a mixed-risk, multi-ethnic cohort of 61 participants with singleton pregnancies. Participants underwent two ultrasound scans at 32-34+0 weeks and 36-38+0 weeks gestation, during which ultrasound detected fetal movements and maternal perception of fetal movements were concurrently recorded. Key demographic and pregnancy characteristics were collected and compared to ultrasound movement data sets. Sensitivity of maternal perception for ultrasound detected fetal movements was calculated.

RESULTS

Neither total ultrasound-detected fetal movements nor maternal perception were significantly associated with placental position, fetal sex, parity, estimated fetal weight centile, or umbilical artery pulsatility index. However, increasing maternal age was associated with more maternally perceived fetal movements at 36-38 weeks (p=0.025, coeff=3.67), and a lower body mass index (BMI) with more ultrasound-detected (p=0.048, coeff=-16.72) and maternally perceived (p=0.025, coeff=-3.62) movements at 36-38 weeks. Using ultrasound detected fetal movements as the gold standard, maternal perception showed a low sensitivity, with no significant difference between gestational ages: perceived movements represented 10.0% of total at 32-34 weeks and 11.4% at 36-38 weeks.

CONCLUSIONS

Although it is widely believed that factors such as placental location, parity, and fetal sex influence fetal movements, we report that only BMI and maternal age had a significant impact on maternal perception of fetal movements. Although the number of ultrasound-detected fetal movements did not increase with maternal age, older participants perceived more fetal movements. Moreover, the association of obesity with lower ultrasound-detected and maternally perceived fetal movements suggests that BMI may independently affect fetal movements and their perception. Maternal perception has a low sensitivity, suggesting that many movements are missed. Maternal perception is therefore not a reliable diagnostic tool, and this may underlie why studies on fetal movements and perinatal outcome are universally negative.