Tobacco smoking and pregnancy is related to many 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 fetus.
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Effects on ongoing pregnancy
Smoking during pregnancy can lead to a plethora of health risks to both the mother and the fetus. Smoking can cause
Early rupture of membranes
Placenta previa
Ectopic pregnancy
Placental abruption.
Smoking cigarettes doubles a woman's risk of developing placental problems. These conditions, as stated above, include premature rupture of membranes, placenta previa, and placental abruption.
Early rupture of membranes
Early rupture of membranes means that the amniotic sac will rupture prematurely, and will induce labor before the baby is fully developed. Although this complication has a good prognosis (in Western countries), it causes severe economic 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.
Placenta previa
Placenta previa is a complication of pregnancy in which the placenta grows in the lowest part of the uterus and covers all or part of the opening to the cervix. Having placenta previa is an economic stress as well because it requires having a caesarean section delivery, which is more expensive and requires a longer recovery period in the hospital. There can also be complications, such as maternal hemorrhage, and this may need to be treated with a blood transfusion. Women with placenta previa need to be carefully monitored by a health care provider. Careful monitoring and delivery by c-section help prevent most complications.
Ectopic pregnancy
An ectopic pregnancy is when the fetus implants itself outside of the uterus. The most common place for the fetus to implant is in the fallopian tubes. Such pregnancies are not viable, and the fetus will die. An ectopic pregnancy must be identified in time, otherwise it can become very dangerous for the mother. The fallopian tube could burst if the fetus becomes too large and the ectopic pregnancy is not identified in time.
Placental abruption
Placental abruption is the premature separation of the placenta from the attachment site. This causes problems for both the mother and the fetus. The fetus can be put in distress, and can even die. The effects of placental abruption on the fetus depend on both the gestational age of the fetus and the severity of the abruption. The mother can loose blood and can have a haemorrhage; she may need a blood transfusion.
Premature birth
Babies born to women who smoke during pregnancy also have roughly 30% higher odds of being born prematurely.
Implications for the umbilical cord
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.
Pregnancy-induced hypertension
There is limited evidence that smoking reduces the incidence of pregnancy-induced hypertension, but not when the pregnancy is with more than one baby (i.e. it has no effect on twins etc.).
Smoking does, however, increase the likelihood of almost every other pregnancy-related health risk to both mother and child, and is the single most preventable cause of illness and death among mothers and infants in the developed world.
Effects of smoking during pregnancy on the child after birth
Low birthweight
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 women who do not smoke. Premature and low birthweight 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), mental retardation and learning problems. Overall, they also face an increased risk of death.
Sudden infant death syndrome
Sudden infant death syndrome (SIDS) is the sudden death of an infant that is unexplainable by the infant’s history. The death also remains unexplainable upon autopsy. Infants exposed to smoke, both during pregnancy and after birth, are found to be more at risk of SIDS due to the increased levels of nicotine often found in SIDS cases. Infants exposed to smoke during pregnancy are up to three times more likely to die of SIDS that children born to non-smoking mothers.
Withdrawal symptoms in child after birth
A 2003 study showed that babies born to mothers who smoked during pregnancy often undergo withdrawal-like symptoms similar to babies born to mothers who used illicit drugs during pregnancy. These babies tend to be more jittery and are harder to soothe than babies born to non-smokers.
Other birth defects
Future obesity
A recent study has proposed that maternal smoking during pregnancy can lead to future teenage obesity. While no significant differences could be found between young teenagers with smoking mothers as compared to young teenagers with nonsmoking mothers, older teenagers with smoking mothers were found to have on average 26 percent more body fat and 33 percent more abdominal fat than similar aged teenagers with non-smoking mothers. This increase in body fat may result from the effect smoking during pregnancy, which is thought to impact fetal genetic programming in relation to obesity. While the exact mechanism for this difference is currently unknown, studies conducted on animals have indicated that nicotine may affect brain functions that deal with eating impulses and energy metabolism. These differences appear to have a significant effect on the maintenance of a healthy, normal weight. As a result of this alteration to brain functions, teenage obesity can in turn lead to a variety of health problems including diabetes (a condition in which the affected individual’s blood glucose level is too high and the body is unable to regulate it), hypertension (high blood pressure), and cardiovascular disease (any affliction related to the heart but most commonly the thickening of arteries due to excess fat build-up).
Future smoking habits
Studies indicate that smoking during pregnancy increases the likelihood of offspring beginning to smoke at an early age.
