Excerpted with permission from
Adventures in Tandem Nursing: Breastfeeding During Pregnancy and Beyond
by Hilary Flower
The hormone oxytocin is often considered to be at the crux of any potential connection between breastfeeding and adverse pregnancy outcomes. When a child suckles, oxytocin is released. Oxytocin is the chemical messenger which causes breast tissue to contract, causing the “let-down” effect which results in milk flow. Through the release of oxytocin and prostaglandin, breastfeeding also stimulates the uterus to contract.
What effect might these breastfeeding-induced contractions have during pregnancy? We do know that mild contractions (known as Braxton-Hicks) are a normal part of pregnancy, and usually breastfeeding contractions are mild during pregnancy. One physician notes that clinical observation shows that breastfeeding contractions do not produce dilation of the cervix.
Accordingly, in the Moscona survey of 57 mothers breastfeeding during pregnancy, only four women (seven percent) recalled contractions related to breastfeeding at all. The four women who did notice contractions described a broad range of strength from mild to intense, and none had an adverse effect on the outcome of pregnancy.
In keeping with Moscona’s findings, a few of my 200 contributors described strong “nursing contractions,” and none resulted in early labor. One mother wrote:
I felt contractions very strongly during my second pregnancy, some so strong that I was afraid of their intensity and ended the nursing session. Some of them were definitely more painful than Braxton-Hicks contractions. I always just called them “nursing contractions” to distinguish them from the so-called “painless” Braxton-Hicks. In every case where I was concerned about the number, duration, or intensity, I was reassured to find that the contractions stopped within about 10-15 minutes of when the nursing session ended. I continued to nurse my son Everest through pregnancy and gave birth to his brother Alden at 39 weeks. I had similar nursing-induced contractions during my next pregnancy, but I was reassured by my previous experiences and did not worry. I continued to nurse both Everest and Alden through that pregnancy, and their baby sister Ellery was born at 39 1/2 weeks.
— Amanda, Massachusetts
The overall lack of noticeable contractions during breastfeeding sessions in pregnancy (even among mothers who did feel Braxton-Hicks contractions) may have a simple explanation. Nipple stimulation during pregnancy causes less oxytocin to be released compared with the same amount of nipple stimulation in non-pregnant women. Some fears of breastfeeding during pregnancy may arise in part from an exaggerated idea of the amount of oxytocin released during breastfeeding in pregnant women.