Pregnancy and child

Vaping and using nicotine patches in pregnancy linked to cot death

"Using e-cigarettes or nicotine patches during pregnancy could increase the risk of cot death in newborns, an early study has found," Sky News reports.

Cot death, referred to by clinicians as sudden infant death syndrome (SIDS), is the sudden, unexpected and unexplained death of an apparently healthy baby.

The causes of SIDS are unknown, but it's thought that environmental stresses such as tobacco smoke or a breathing obstruction could play a role.

As part of this study, researchers exposed unborn rats to nicotine. When they were born, they tested their response to low oxygen levels, looking at mice pups both with and without a serotonin deficiency.

Serotonin is a neurotransmitter (chemical messenger) usually associated with mood disorders such as depression.

But the chemical also plays an important role in regulating breathing. It's thought to stimulate what's known as autoresuscitation.

This is an automatic response from the nervous system that causes the body to gasp for air if oxygen levels drop to a dangerously low level.

The study found nicotine exposure affected the ability to respond to lack of oxygen in rats with an induced serotonin deficiency.

Nicotine exposure or serotonin deficiency alone wasn't found to hinder their ability to recover from oxygen deprivation.

The concern is that a similar effect could happen in babies born to mothers with a pre-existing serotonin deficiency who use nicotine products during pregnancy.

Of course, using nicotine replacement products in pregnancy is still far healthier for both you and your baby than continuing to smoke. But, ideally, you should avoid exposure to nicotine entirely.

Where did the story come from?

The study was carried out by a team of researchers from the US Geisel School of Medicine at Dartmouth.

It was funded by a grant from the National Institutes of Health (NIH).

The study was published in the peer-reviewed Journal of Physiology.

The UK media's reporting of the study was accurate, but failed to mention the importance of serotonin in the study.

Also, the headline writers failed to make it clear that this research involved rats, not humans.

What kind of research was this?

This study in rats aimed to investigate whether nicotine exposure during pregnancy is linked with an increased risk of SIDS.

Animal studies are important in early-stage scientific research, and can be used to get an indication of biological processes and how things might work in humans.

But while genetically there are many similarities between rats and humans, there are obviously great differences.

The findings from animal studies can't necessarily be applied to humans.

Carrying out this sort of randomised study in humans would be unethical, as it could expose both mothers and babies to harm.

One possible solution would be to study women who voluntarily chose to use nicotine during their pregnancy and see if this had an effect on health outcomes (use a cohort study design).

What did the research involve?

The researchers fed adult female rats either a tryptophan-rich diet or a tryptophan-poor diet (half the amount).

Tryptophan is an amino acid found in a wide range of protein-rich foods, such as eggs, cheese and chicken. The body can convert tryptophan into serotonin.

Previous research has shown that regularly eating a tryptophan-poor diet will lower serotonin levels in the body and cause a serotonin deficiency.

The rats were then allowed to mate. This produced rat pups that were either serotonin deficient or had normal levels (the controls).

During pregnancy, half of the rats in each group were exposed to nicotine through an implant. The other half were given a salt water implant to act as a control.

The researchers then assessed the rat pups' ability to respond to repeated periods of low oxygen.

They compared findings between the rats with serotonin deficiencies and those without, and between those that had been exposed to nicotine or not.

What were the basic results?

Nicotine exposure during pregnancy was found to hinder the ability of serotonin-deficient rats to autoresuscitate when placed in oxygen-deprived situations, more so than the rats in the control group.

It took serotonin-deficient rats much longer to recover back to normal breathing and heart rates following a period of oxygen deprivation.

Exposure to nicotine or serotonin deficiency alone wasn't found to negatively affect the recovery of rats following oxygen deprivation.

How did the researchers interpret the results?

The researchers said: "We speculate that maternal nicotine exposure places infants who have other vulnerabilities, e.g. mild 5-HT [serotonin] deficiency, at high risk for an impairment of protective response to severe hypoxia, anoxia and asphyxia [oxygen deprived situations].

"With increasing numbers of nicotine patch and electronic cigarette users during pregnancy, there is an increasing urgency to better understand the impact of developmental nicotine exposure on the health of neonates, especially those who are more vulnerable with an intrinsic medullary 5-HT defect [reduced serotonin levels]."


This animal study aimed to investigate whether nicotine exposure during pregnancy is linked with an increased risk of SIDS.

The researchers found that nicotine exposure affected the ability of serotonin-deficient rats to respond positively to situations of oxygen deprivation.

Nicotine exposure or serotonin deficiency alone weren't found to hinder the ability to recover from oxygen deprivation.

This interesting study serves as valuable early-stage research that could pave the way for further studies looking into the interaction between nicotine exposure and SIDS.

The researchers hope this study will spur more investigation into the use of e-cigarettes and nicotine patches during pregnancy.

But bear in mind that this is an animal study. Further studies in humans is required to validate these findings.

A cohort study would be one of the best ways to look into this further, as randomised controlled trials wouldn't be ethical.

Currently, the NHS recommends the following ways to reduce the risk of SIDS:

  • place your baby on their back to sleep, in a cot in the same room as you, for the first 6 months
  • don't smoke during pregnancy or breastfeeding, and don't let anyone smoke in the same room as your baby
  • don't share a bed with your baby if you have been drinking alcohol, if you take drugs, or you're a smoker
  • never sleep with your baby on a sofa or armchair
  • don't let your baby get too hot or cold
  • keep your baby's head uncovered – their blanket should be tucked in no higher than their shoulders
  • place your baby in the "feet to foot" position, with their feet at the end of the cot or Moses basket

If you're a smoker planning a pregnancy, possibly the best option is to use nicotine replacement therapies (NRTs), such as patches, to help you quit smoking before trying for a baby.

Read more advice about planning for a pregnancy.

NHS Attribution