Smoking during pregnancy increases your risk of problems like birth defects and preterm delivery. It also increases your baby’s risk for low birth weight and SIDS.
Cigarette smoke contains carbon monoxide, which replaces some of the oxygen in your bloodstream and reduces the amount of oxygen that passes through the umbilical cord to your baby.
Smoking During Pregnancy – Premature Delivery
A woman’s smoking can cause complications that lead to premature delivery. This means that labor starts before the 37th week of pregnancy, and it’s a major source of infant deaths. Babies born too early have health problems at birth and later in life. Prematurity is caused by a number of factors, including pre-eclampsia (high blood pressure and swelling) and placenta previa. Placenta previa occurs when the placenta grows to the point where it covers the cervix, blocking off oxygen from the fetus and causing excessive bleeding.
Smoking can also increase your chances of having a low birth weight baby, which can have long-term effects on your child’s health and development. It’s thought that this happens because cigarette smoke makes the mother’s heart beat faster, which reduces the amount of oxygen in her bloodstream.
A large study found that women who smoked before and during pregnancy had higher rates of spontaneous or medically-indicated preterm birth and very preterm birth than nonsmokers. The researchers suggest that cigarette smoking causes these negative outcomes through various biological pathways, including nicotine-induced vasoconstriction, carbon monoxide-induced fetal hypoxia, cadmium disruption of calcium signaling, altered steroid hormone production and disrupted prostaglandin synthesis, and changed responses to oxytocin. They also suggested that the effect may be due to the combination of these pathways. Women who quit smoking early in their pregnancy significantly reduced their risk of these adverse outcomes.
Smoking During Pregnancy – Low Birth Weight
The smoke from a cigarette contains over 4,000 chemicals and reduces the amount of oxygen that can reach a developing baby. Babies born with low birth weight are at a higher risk of death and have a greater chance of suffering from life-long health problems. It is important for women to get good prenatal care and to avoid smoking, especially if they have other chronic health conditions, such as high blood pressure, asthma and heart, lung or kidney problems.
The National Center for Disease Control and Prevention (NCDS) found that babies whose mothers smoked during pregnancy were less likely to have a healthy birthweight. They also performed worse on cognitive assessments and had lower reading ages at school than their non-smoking peers. This result was enough to prompt a national campaign to educate pregnant women on the risks of smoking during pregnancy.
In addition, a study published in PLoS One showed that nicotine causes contractions of the fallopian tubes, which can prevent an embryo from implanting in the uterus. This type of pregnancy, called an ectopic pregnancy, must be terminated to prevent life-threatening complications for the mother and the fetus.
Studies have shown that smoking is associated with a number of other birth defects, such as orofacial clefts and apnea, placenta previa and abruptio placenta, intrauterine growth restriction, respiratory and gastrointestinal diseases and transfer to the neonatal intensive care unit. In addition, heavy smoking during pregnancy is linked to an increased risk of spontaneous abortion and maternal deaths.
Smoking During Pregnancy – Ectopic Pregnancy
If the fertilized egg cannot make its way down the fallopian tube, it is called an ectopic pregnancy. This is dangerous for both the mother and the baby. It can cause the fallopian tube to rupture, and the woman could experience severe bleeding and even death. This problem occurs because of infections, inflammations or scar tissue that block the tube. Women who have been treated for pelvic inflammatory disease are more likely to have an ectopic pregnancy. Infertility treatments, including intrauterine device (IUD) placement and tubal ligation, also raise the risk of ectopic pregnancy.
Cigarette smoke increases the rate of ectopic pregnancies by reducing the production of a gene in the Fallopian tubes. This is why it’s important to avoid smoking before trying to get pregnant and continue to stay smoke-free if you are already pregnant.
Smoking during pregnancy also increases the chance of having a low birth weight baby, which is harmful to both mom and baby. Babies born at low birth weight are at a higher risk of serious health problems in early childhood, and throughout life. They may also face problems that can be life-threatening, like Sudden Infant Death Syndrome (SIDS) or pulmonary dysfunction and respiratory failure.
Smoking During Pregnancy – Sudden Infant Death Syndrome
Babies born to smoking mothers have a much higher risk of sudden infant death syndrome, or SIDS. This is because the chemicals in secondhand smoke—such as tar, carbon monoxide and nicotine—pass through the placenta and umbilical cord to the baby. This lessens the amount of oxygen and important nutrients that reach the baby. This is especially dangerous for preterm babies.
Smoking also can cause a woman to experience complications during labor and delivery. These include premature birth—labor that begins before the 37th week of pregnancy—and a low birth weight. Preterm babies have a lot of health problems and are more likely to die at birth or in early childhood.
Another serious problem that can result from smoking during pregnancy is ectopic pregnancy. This is when a fertilized egg implants in the fallopian tube or in the abdomen instead of in the uterus. It is life-threatening for both mother and baby.
In a recent study, researchers found that infants of smokers had double the risk of SIDS compared to babies of nonsmokers. The study used data from the Centers for Disease Control and Prevention on more than 20 million births and about 18,000 cases of SUID in infants up to age 1. However, the researchers did not have information on the amount of smoking by men or others who lived with pregnant women, so it is difficult to determine whether postnatal exposure to secondhand smoke might have contributed to the increased risk of SUID in infants born to mothers who smoked.
