Gravidity, Gestation, New Pregnancy

Depending on different cultures, between 5% and 60% of women who become pregnant while still breastfeeding continue breastfeeding during pregnancy ^{(Bayraktar 2025, Çınar 2022, Molitoris 2019, López 2017, Merchant 1990)}

It is possible to continue breastfeeding during a new pregnancy. By ensuring the necessary additional dietary intake, breastfeeding is considered compatible with a new pregnancy and without risk to the mother, the nursing child, or the unborn baby ^{(CLM 2012, HWA 2009)}. The Working Group on Breastfeeding of the Italian Society of Perinatal Medicine has taken this position ^{(Cetin 2014)}. Breastfeeding during a subsequent pregnancy is not unusual. If the pregnancy is normal and the patient is healthy, breastfeeding during pregnancy is a personal decision. ^{(AAFP 2022)}

No differences have been found in pregnancy duration, newborn weight, subsequent growth, or miscarriage rates between healthy, well-nourished pregnant women who continue breastfeeding and those who do not. ^{(Stalimerou 2023, Minh 2021, Molitoris 2019, López 2017, Shaaban 2015, Pareja 2015, Ayrim 2014, Cetin 2014, Madarshahian 2012, Ishii 2009, Moscone 1993)}

Breastfeeding during pregnancy does not produce adverse outcomes for either the mother or the fetus in a normal low-risk pregnancy, although it may create a nutritional burden for the mother ^{(Minh 2021)}. Nutritional, energy, mineral, and vitamin requirements are very high during pregnancy and even higher during lactation ^{(Molitoris 2019)}, which should be especially considered in economically disadvantaged populations to avoid reduced weight gain, decreased hemoglobin levels, and other problems in women who breastfeed during pregnancy. ^{(Shaaban 2015, Ayrim 2014; Marquis 2003 and 2002, Siega 1993)}

Although nipple stimulation has been used to promote cervical ripening and induce labor ^{(Kavanagh 2005)}, there is no evidence that the oxytocin released during breastfeeding can induce preterm labor or miscarriage ^{(Molitoris 2019)}, because the oxytocin peak is not sufficient and uterine oxytocin receptors are not fully developed until the end of pregnancy ^{(López 2017)}. A retrospective study with many limitations showed a higher risk of spontaneous abortion with exclusive breastfeeding during pregnancy, but not with breastfeeding alongside complementary feeding ^{(Molitoris 2019)}, which would actually be attributable to the almost zero spacing between pregnancies that the first option implies.

Historically, breastfeeding has been a method of spacing pregnancies; however, beyond the first 6 months and unless practiced exclusively and intensively (LAM method), it cannot be considered a contraceptive method and is not incompatible with planning a new pregnancy. ^{(AAFP 2022, WHO 2009, Tikka 1998, Short 1991, Chao 1987)}

Higher levels of estrogen and progesterone during pregnancy ^{(WHO 2009)} explain some changes in milk composition (lower amounts of fat and lactose and higher levels of protein, sodium, IgA, lactoferrin, and lysozyme), which become more pronounced as pregnancy progresses, approaching colostrum composition toward the end of pregnancy ^{(Ismail 2009)}. These changes are not nutritionally harmful to the infant, especially since in these cases the infant is usually much older than 6 months ^{(Bayraktar 2025)} and therefore receives complementary feeding.

The factors implicated in the higher frequency of weaning during pregnancy include possible changes in milk taste, a possible decrease in milk production ^{(WHO 2009)}, increased breast sensitivity, maternal aversion to continued breastfeeding, cultural taboos and beliefs, social pressure, and professional advice. ^{(Çınar 2022, Moscone 1993)}

If breastfeeding continues throughout the entire pregnancy, the breast produces colostrum again around the time of birth and the immediate postpartum period.