Normal fetal movements can be defined as 10 or more fetal movements in 2 hours, felt by a woman when lying on her side and focused on the movement, which may be perceived as “kicking, fluttering, snapping, or rolling”.
Fetal movements ensure the integrity of the central nervous and musculoskeletal systems. Most pregnant women report fetal movements at 20 weeks gestation.
The average number of perceived movements at term is 31 per hour, with a range of 16 to 45, with the longest period between movements being 50 to 75 minutes. Sleep cycles, in which fetal movements may be absent, generally last 20 to 40 minutes and rarely exceed 90 minutes. As the fetus matures, the amount of movement and the nature of the movement will change.
Fetal movement is a subjective measure, assessed primarily by maternal perception. Research has shown that there is a 37–88% correlation between maternal perception and ultrasound.
Multiple factors can decrease motion perception, including early gestation, reduced amniotic fluid volume, fetal sleep status, obesity, anterior placenta (up to 28 weeks' gestation), smoking, and nulliparity.
A simple explanation given by some women with decreased fetal movements is that they have been "too busy to feel fetal movements." It is known that less movement is perceived when women are standing or sitting, compared to lying down or concentrating on movements. It is commonly thought that drinking a cold drink or eating something sugary will stimulate fetal movement, but there is no evidence to suggest that either of these will affect movement.
If there is uncertainty surrounding perceived fetal movements after 28 weeks' gestation, women should be advised to lie on their left side and focus on fetal movements for 2 hours. If they do not feel 10 or more discrete movements in 2 hours, they should contact their OB/GYN. However, the mother's concern about decreased fetal movement warrants evaluation.
El Dr. Daniel García, gynecologist and obstetrician at Ginefem, explains in this video if you should go to the emergency room if you notice that your baby is not moving.
