Smoking and Pregnancy

Smoking effects on growth and weight

When you smoke, you breathe carbon monoxide which goes into your vital oxygen supply.   This in turn goes into our baby’s body and as a result, your baby will not have optimal growth conditions.  Smoking therefore means that birth weight is lower than if the mother did not smoke.  Children born to smokers weigh on average 250 grams (½lb) less than children of non-smokers.  Smokers are twice as likely to have children who weigh less than 2,500 grams (5½lb), compared to non-smokers.

Babies are more likely born with a high dependence (the need for additional oxygen etc) if you smoke. Organs such as the brain, lungs, kidneys etc. may take longer to mature.  Babies of smoking parents may struggle more in the first few days of life.

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Smoking effects on breastfeeding

Establishing breastfeeding can be harder for the smoking mother.  Breast milk supply tends to be lower due to the reduced amount of prolactin in the mother’s body, as a result of the nicotine in the blood stream, and babies of smokers tend to suffer more from colic.

Passive smoking can also directly affect your baby’s immune system and whilst breastfeeding can reduce your baby’s risk of infections, if the mother smokes this can increase the risk further.  There is strong scientific evidence to suggest that smokers tend to wean their babies earlier than non smokers.

Nicotine reduces the amount of iodine passed to the baby in breast milk and as a result, baby can suffer from vomiting, nausea, abdominal cramps and diarrhoea.  Protection for your baby against thyroid infections and brain problems is also reduced if the mother smokes.

Smoking effects on sudden infant death

Smoking and breastfeeding may reduce your baby’s resistance against sudden infant death syndrome.

There is greater risk of SIDS if the mother continues to smoke during pregnancy and beyond.  Even a mother who quits during the pregnancy and starts again after birth is putting their child at a much higher risk of cot death.

Children of mothers who smoked during pregnancy have more respiratory infections and are at higher risk of developing asthma and allergies.  The same applies to children after birth who are exposed to passive smoking.  Children exposed to passive smoking also have more hospital admissions than other children.

Benefits to the mother of quitting:

  • Less risk of miscarriage
  • Less risk of placenta praevia
  • Less risk of placenta abruption
  • Less risk of giving birth prematurely
  • Less risk of a still birth

If you are concerned about weight gain caused by quitting smoking, now is a great opportunity to stop without gaining weight, because breastfeeding is a very energy consuming process and any additional calories consumed as a result of quitting, are burnt off easily during breastfeeding.

Can pregnant women use nicotine products?

Nicotine patches and gum are not recommended for pregnant women.   If you are unable to quit without them, you will need to talk to your doctor about alternatives or whether he feels it would be right for you to use nicotine products.

Smoking effects on fertility

Women who smoke have a decreased monthly probability of achieving pregnancy.

Smoking during pregnancy also reduces the child’s future monthly probability of achieving pregnancy when it is grown up, regardless of whether the child is a boy or girl.

Smokers also have a smaller chance of a good outcome of fertility-enhancing treatment than non-smokers, but quitting smoking improves the chance.   A recent study in Denmark shows that smoking is the explanation for approximately  one sixth of the annual event of involuntary childlessness in the world.


What hints and tips can you give other mums who are trying to quit smoking? Did you restart again after your baby was born?