Miscarriage rate in pregnancy–breastfeeding overlap

Does Contraceptive Use Always Reduce Breast-feeding?

Previous studies suggest that access to modern contraceptives can reduce breast-feeding rates because women who had been using breast-feeding to avoid pregnancy substitute away from it. This article shows that contraceptive use can also have a positive effect on breast-feeding. A mother often weans a child if she becomes pregnant again, which can occur sooner than desired if she lacks access to contraceptives. Thus, by enabling longer birth spacing and preventing unwanted pregnancies, contraceptive use allows for a longer duration of breast-feeding. This positive effect should primarily affect infants who are past the first few months of life because their mothers are more fecund then, and the negative effect should affect infants who are very young because the contraceptive property of breast-feeding is strongest then. I test for these dual effects using Demographic and Health Survey data for Indonesia. I find evidence of the positive birth-spacing effect: contraceptive use increases the likelihood that children continue to be breast-fed past age 1. There is also suggestive evidence of a negative substitution effect among infants age 3 months and younger.

Breastfeeding during pregnancy: position paper of the Italian Society of Perinatal Medicine and the Task Force on Breastfeeding, Ministry of Health, Italy

As more women breastfeed for longer, it is increasingly likely that women may be still breastfeeding when they become pregnant again. The Italian Society of Perinatal Medicine (SIMP) Working Group on Breastfeeding has reviewed the literature to determine the medical compatibility of pregnancy and breastfeeding. We found no evidence indicating that healthy women are at higher risk of miscarriage or preterm delivery if they breastfeed while pregnant. No evidence indicates that the pregnancy-breastfeeding overlap might cause intrauterine growth restriction, particularly in women from developed countries. Little information is available on the composition of human milk of pregnant women, and we found no data on the growth of infants nursed by a pregnant woman. However, both the composition of postpartum breast milk and the growth of the subsequent newborn appear to be partly affected, at least in developing countries. SIMP supports breastfeeding during pregnancy in the first 2 trimesters, and we believe it to be sustainable in the third trimester. Based on the hypothetical risk, caution may be warranted for women at risk of premature delivery, although no evidence exists that breastfeeding could trigger labor inducing uterine contractions. In conclusion, currently available data do not support routine discouragement of breastfeeding during pregnancy. Further studies are certainly needed to explore the consequences of breastfeeding during pregnancy on maternal health, on the breastfed infant, on the embryo/fetus, and, subsequently, on the growth of the newborn.