How are Low Birthweight and Smoking Related?

A mother who smokes during pregnancy is almost two times as likely to give birth to a low birthweight baby than a mom who doesn’t smoke. This means a baby who weighs less than 5 pounds, 8 ounces at birth.

Nicotine constricts the blood vessels in the umbilical cord and the womb. This reduces how much oxygen your baby gets. Smoking also keeps your baby from getting nourishment. As a result, smoking has a negative effect on all stages of pregnancy. It may also cause problems during delivery. For instance, the placenta can break away from the womb too early and cause bleeding. This is called placental abruption.

A baby whose mother smokes may be born too early. The baby may even die before birth. Babies born to women who smoke also have less muscle mass and more fat than those born to women who don’t smoke.

Smoking can affect a baby’s health even after he or she is born. If a woman smokes before and after birth, her child has much higher risk for sudden infant death syndrome (SIDS). This is the unexplainable death of a child younger than age 1 year. Children who were born with low birthweight are at greater risk for health issues later in life. These include diabetes, high blood pressure, heart disease, and obesity.

If you haven't quit smoking yet, get help to quit now. The sooner you quit smoking, the healthier your baby and you will be. Visit  to learn more about quitting.

Online Medical Reviewer: Bowers, Nancy, RN, BSN, MPHFoley, Maryann, RN, BSN

Date Last Reviewed: 4/12/2016

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