Introduction: Around the world, as well as in Turkey, women breastfeed their infants as long as possible. There is, however, a strong cultural taboo against continuing breastfeeding while having a new pregnancy. The aim of this study was to evaluate the outcome of pregnancies occurring during the lactation period and to determine whether lactation throughout the pregnancy had any adverse effects. This is the first study in Turkey to provide data on the association between the practice of lactation throughout pregnancy and outcome.

Subjects and Methods: One hundred sixty-five multiparous women with singleton pregnancies who were =18 years of age, breastfeeding the previous child, and did not have systemic disease were included. Forty-five of the 165 pregnant women continued lactating, whereas 120 did not. We compared weight gain during pregnancy, hemoglobin level alterations, pregnancy complications, neonatal weight, and Apgar scores between the two groups.

Results: Lactating pregnant women gained less weight than the nonlactating group, and the decreased level of hemoglobin during pregnancy was significant in the lactating group. Between the two groups, there was no statistically significant difference in hyperemesis gravidarum, threatened abortion, preeclampsia, premature labor and birth, neonatal weight, or Apgar scores.

Conclusions: Breastfeeding during pregnancy is not harmful, and health professionals should not advise weaning if overlapping occurs and should observe mother, infant, and fetus closely for negative effects, and if a negative effect occurs they should take precautions.