Low birth weight is more common than stillbirth, affecting 20 million babies annually  and increasing infant mortality by twenty times in the first year of life .
Assuming a supine position during the third trimester causes significant hemodynamic changes including a reduction of maternal cardiac output and subsequently a reduction in blood flow to the fetus. A study investigating the effect of supine maternal position on birth weight found that women at 28 weeks of gestation or greater who often slept in a supine position had a baby with an average birth weight of 3410g (compared to an average of 3554g for women who did not sleep in a supine position) and a mean reduction of 10% in birth weight centile independent of other factors that affect birth size. There was also a three-fold increase in odds of small for gestational age by INTERGROWTH-21st centiles for women that went to bed in a supine position .
A cross-sectional study investigating maternal sleep practices and fetal outcomes for Ghanian women found that maternal supine sleep contributes significantly to pre-eclampsia, low birth weight, and stillbirth .