Smoking and pregnancy

Tobacco smoking during pregnancy causes many detrimental effects on health and reproduction, in addition to the general health effects of tobacco. A number of studies have shown that tobacco use is a significant factor in miscarriages among pregnant smokers, and that it contributes to a number of other threats to the health of the foetus.^[1][2][3]

Because of the associated risks, people are advised not to smoke before, during or after pregnancy. If this is not possible, however, reducing the daily number of cigarettes smoked can minimize the risks for both the mother and child. This is especially true for people in developing countries, where breastfeeding is essential for the child's overall nutritional status.^[4]

Smoking before pregnancy

Women who are pregnant or planning to become pregnant are advised to stop smoking.^[5][6] It is important to examine these effects because smoking before, during and after pregnancy is not an unusual behavior among the general population and can have detrimental health impacts, especially among both mother and child, as a result. In 2011, approximately 10% of pregnant women in data collected from 24 U.S. states reported smoking during the last three months of their pregnancy.^[7]

According to a 1999 meta-analysis published in the American Journal of Preventive Medicine, smoking prior to pregnancy is strongly related to an increased risk of developing an ectopic pregnancy.^[6]

Smoking during pregnancy

According to a study conducted in 2008 by the Pregnancy Risk Assessment Monitoring System (PRAMS) that interviewed people in 26 states in the United States, approximately 13% of women reported smoking during the last three months of pregnancy. Of women who smoked during the last three months of pregnancy, 52% reported smoking five or fewer cigarettes per day, 27% reported smoking six to 10 cigarettes per day, and 21% reported smoking 11 or more cigarettes per day.^[8]

In the United States, women whose pregnancies were unintended are 30% more likely to smoke during pregnancy than those whose pregnancies were intended.^[9]

Effects on ongoing pregnancy

Smoking during pregnancy can lead to a plethora of health risks and damage to both the mother and the fetus.

Women who smoke during pregnancy are about twice as likely to experience the following

• premature rupture of membranes
  , which means that the amniotic sac will rupture prematurely, and will induce labour before the baby is fully developed. Although this complication generally has a good prognosis (in Western countries), it causes stress as the premature child may have to stay in the hospital to gain health and strength to be able to sustain life on their own.
• placental abruption, wherein there is premature separation of the placenta from the attachment site. The fetus can be put in distress, and can even die. The mother can lose blood and can have a haemorrhage; she may need a blood transfusion.
• placenta previa, where in the placenta grows in the lowest part of the uterus and covers all or part of the opening to the cervix.^[11] Having placenta previa is an economic stress as well because it requires having a caesarean section
  delivery, which require a longer recovery period in the hospital. There can also be complications, such as maternal hemorrhage.

According to a 1999 meta-analysis published in the American Journal of Preventive Medicine, smoking during pregnancy is related to a reduced risk of developing pre-eclampsia.^[6]

Premature birth

Some studies show that the probability of

Smoking can also impair the general development of the placenta, which is problematic because it reduces blood flow to the fetus. When the placenta does not develop fully, the umbilical cord which transfers oxygen and nutrients from the mother's blood to the placenta, cannot transfer enough oxygen and nutrients to the fetus, which will not be able to fully grow and develop. These conditions can result in heavy bleeding during delivery that can endanger mother and baby, although cesarean delivery can prevent most deaths.^[13]

Pregnancy-induced hypertension

There is limited evidence that smoking reduces the incidence of

Smoking during pregnancy can result in lower birth weight as well as deformities in the fetus.[18]^[19] Smoking nearly doubles the risk of low birthweight babies. In 2004, 11.9% of babies born to smokers had low birthweight as compared to only 7.2% of babies born to nonsmokers. More specifically, infants born to smokers weigh on average 200 grams less than infants born to people who do not smoke.^[20]

The nicotine in cigarette smoke constricts the blood vessels in the placenta and carbon monoxide, which is poisonous, enters the fetus' bloodstream, replacing some of the valuable oxygen molecules carried by hemoglobin in the red blood cells. Moreover, because the fetus cannot breathe the smoke out, it has to wait for the placenta to clear it. These effects account for the fact that, on average, babies born to smoking mothers are usually born too early and have a low birth weight (less than 2.5 kilograms or 5.5 pounds), making it more likely the baby will become ill or die. ^[21]

Premature and low birth weight babies face an increased risk of serious health problems as newborns have chronic lifelong disabilities such as cerebral palsy (a set of motor conditions causing physical disabilities), intellectual disabilities and learning problems.

If you are smoking during the

Smoking can also cause other birth defects, reduced head circumference, altered brainstem development, altered lung structure, and cerebral palsy. Recently the U.S. Public Health Service reported that if all pregnant women in the United States stopped smoking, there would be an estimated 11% reduction in stillbirths and a 5% reduction in newborn deaths.[20]

Future obesity

A recent study has proposed that maternal smoking during pregnancy can lead to future teenage