Smoking and pregnancy

Published by Bupa's Health Information Team, December 2010.

Smoking not only damages your health, your looks and your wallet, it can seriously affect your ability to conceive a child and can be harmful during pregnancy, for both you and your baby. It can also affect your partner’s fertility and damage his sperm whether it’s him who smokes or you. For many women, trying to have a baby or actually getting pregnant is great motivation for stopping smoking and improving their general health.

But exactly what problems does smoking cause? This article will give you an idea of how smoking affects you and your baby before, during and after pregnancy.

Before you become pregnant

Smoking increases your risk of a number of health problems, but it can also reduce your chances of getting pregnant.

The good news is that if you stop smoking, your fertility should improve and you will be as likely to conceive as someone who doesn’t smoke.

Problems during pregnancy

If you smoke, you’re more likely to have complications during your pregnancy and labour. These can include:

• ectopic pregnancy – this is when the fertilised egg implants and grows outside the womb, usually in a fallopian tube; fewer than five cigarettes a day increases the risk by 60 percent
  
• miscarriage – this is when your baby dies before 24 weeks of pregnancy
  
• pre-eclampsia – this causes high blood pressure and can lead to growth problems for your baby or premature birth
  
• placental abruption – this is when the placenta comes away from the wall of the womb, which can sometimes cause your baby to die before or soon after birth
  
• placenta praevia – this is when the placenta blocks your cervix (neck of your womb), which can cause bleeding or premature birth
  
• premature labour – this is when you go into labour before 37 weeks of pregnancy

Smoking is also responsible for the deaths of a third of all babies who die after 24 weeks of pregnancy and before they are four weeks old.

Problems for your developing baby

If you smoke during pregnancy, the carbon monoxide in the cigarette smoke prevents oxygen from getting to your developing baby. This can slow growth and affect your baby’s brain development. But that’s not all – the chemicals in smoke can also damage your baby during pregnancy.

And it all builds up – the more you smoke, the greater the risk of problems for your baby, including:

• being born too early – babies whose mothers smoke are twice as likely to be premature
  
• low birth weight – this means your baby is born weighing less than 2,500g (5lb 5oz); babies born to women who smoke are, on average, 200 to 250g lighter than those of non-smokers
  
• having a birth defect – if you smoke, it can affect your baby’s development and cause problems such as cleft lip or palate or a problem with his or her limbs, urinary system or genitals

Problems after your baby is born

Smoking during pregnancy can increase the risk of cot death. Cot death, or ‘sudden unexpected death of an infant’ (SUDI), is when a child dies before the age of two and no cause can be found. It’s most common when your baby is between two and four months old. The risk of SUDI is three times higher if you smoke during and after pregnancy. Scientists don’t know exactly why SUDI happens, but it may be caused by problems with the processes that regulate heartbeat and breathing. It’s possible that smoking affects your baby’s brain development so that he or she is born before the brain can correctly control the heart and lungs.

Smoking can also affect the development of your baby’s lungs, making them less effective. This can continue to affect your child as he or she gets older and can cause chronic obstructive pulmonary disease (COPD).

Your baby may be more likely to have colic. All babies cry but if your baby has colic, you’ll really know about it. He or she will cry for several hours a day, seemingly for no reason, which can be extremely stressful for all concerned.

If you carry on smoking after your baby is born, you may be creating further health problems for him or her later in life, including:

• asthma
  
• respiratory infections such as croup and pneumonia
  
• ear infections
  
• childhood cancer
  
• being small for his or her age
  
• lower achievement at school

Breastfeeding

Breastfeeding is a great way to make sure your baby gets all the nutrition he or she needs in the first six months of his or her life. Breast milk is also good for your baby’s health – it helps to protect against infections and reduces the risk of SUDI or asthma.

However, another issue with smoking is that it can affect how well you can breastfeed. This is because it reduces the amount of milk you produce, possibly because it affects the hormone prolactin, which you need to produce breast milk. Any milk you do produce is usually of poorer quality and often doesn’t have enough of the fats that your baby needs.

If you smoke, you’re also more likely to stop breastfeeding earlier than a non-smoker.

For sources and links to further information, see Resources.