Smoking and Baby IQ

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Pregnancy is a critical period in which maternal health can significantly affect the health and development of the unborn child. Factors such as maternal smoking and polycystic ovary syndrome (PCOS) have been linked to various adverse outcomes for the child.

Maternal smoking during pregnancy is a well-established risk factor for adverse outcomes such as low birth weight, respiratory problems, and sudden infant death syndrome. A study published in 2005 found that offspring of mothers who smoked during pregnancy scored, on average, 6.8 IQ points lower than offspring of mothers who never smoked. This IQ deficit was not observed in offspring of mothers who smoked but had higher cognitive ability, as measured by IQ and education. This suggests that maternal characteristics, rather than smoking itself, may be responsible for the association between maternal smoking and lowered IQ in offspring.

On the other hand, low birth weight is a well-known risk factor for various health problems in children, including developmental delays and lowered IQ. A study found that low birthweight children scored, on average, 5.4 IQ points lower than normal birthweight children. Unlike the case with maternal smoking, adjusting for maternal IQ and education as well as low birthweight did not eliminate the IQ deficit. This suggests that low birth weight itself may be responsible for the lowered IQ in these children, rather than maternal characteristics.

Another condition that can affect maternal and fetal health is PCOS, a common endocrine disorder that affects 6 to 15% of reproductive age women worldwide. PCOS is associated with various complications during pregnancy, including an increased risk of miscarriage, gestational diabetes mellitus, hypertensive disorders of pregnancy, preterm delivery, and birth of small for gestational age infants.

A study found that PCOS women are at a higher risk of early pregnancy loss (EPL), defined clinically as first-trimester miscarriage, compared with normal women. EPL occurs in 30 to 50% of PCOS women, compared with 10 to 15% of normal women. This highlights the importance of early detection and management of PCOS in reproductive-age women, particularly those planning to conceive.

In conclusion, maternal health factors such as smoking and PCOS can have significant impacts on fetal and child health. While the association between maternal smoking and lowered IQ in offspring appears to be mediated by maternal characteristics, low birth weight itself may be responsible for the lowered IQ in children born with this condition. PCOS is associated with various pregnancy complications, including an increased risk of EPL. Early detection and management of these conditions are crucial to ensure optimal maternal and child health outcomes.


Breslau, N., Paneth, N., Lucia, V. C., & Paneth-Pollak, R. (2005). Maternal smoking during pregnancy and offspring IQ. International journal of epidemiology, 34(5), 1047–1053.






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