Smoking During Pregnancy: Giving Up By Month 5 Can Prevent Underweight Babies

In the latest of a series of interviews from the Royal Economic Society Conference 2007, Romesh Vaitilingam talks to Emma Tominey about the effect of smoking during pregnancy.

Mothers who smoke during pregnancy will have smaller babies. But much of the harm is due to unobservable traits of the mother. If mums stub it out by the time they are five months pregnant, the damage is as good as undone.

At the same time, the lasting harm to babies is greatest if the mothers have low education. So a much more holistic approach to improving child health in pregnancy is needed to help thousands of children break out of the poverty trap.

These are the conclusions of extensive new research by Emma Tominey, presented to the Royal Economic Society’s 2007 annual conference at the University of Warwick, 11-13 April.

Babies born to women who smoke will typically be 5.4% (6.5oz) lighter than other babies. But around half of this damage is because of unobservable traits of the mother. This means that stopping mothers smoking during pregnancy is important, but it is only half of the battle.

So while the effects of being a small baby stay with a child throughout its life, affecting its health, education and earnings potential, stopping a mother from smoking must be combined with helping her to be healthier in other areas of her life.

But for the harm that remains, the low educated mothers are hardest hit. Children born to mothers who left school at the age of 16 suffer double the harm for each cigarette smoked. The government must target its policy directly at these low educated families.

Women who do smoke in the early stages of pregnancy should not be ‘written off’ as ‘too late’. Surprisingly, the research shows that the harm to the baby is essentially reduced to zero if the mother quits by month five of the pregnancy.

This is much longer than conventional wisdom and previous research has suggested and tells us there’s more time than we thought to help the mothers change their behaviour during pregnancy.

The study is based on research into the lives of 6,500 children and their mothers, and went into exceptional detail of the mother’s lifestyle over her lifetime. The mothers were tracked from their child’s birth until the age of 42.

The research suggests that while previous studies have identified a link between smoking and low birth weight, none has looked in such depth at whether the experiences of the mother can alter this and how the harm accumulates during pregnancy.

The study calls on the government to alter radically its policy on helping pregnant women quit smoking, developing a more holistic approach to improving the health of these children during pregnancy and targeting the children of low educated mothers.

Notes for editors: Maternal Smoking During Pregnancy and Child Birth Weight by Emma Tominey was presented at the Royal Economic Society’s 2007 annual conference at the University of Warwick, 11-13 April.

Emma Tominey is at University College London.

For further information: contact Romesh Vaitilingam on 07768-661095 (email:

Read more papers by Emma Tominey at EconPapers and search for more Internet resources on the issue of Women and Economics at Intute: Social Sciences.

7 Responses to “Smoking During Pregnancy: Giving Up By Month 5 Can Prevent Underweight Babies”

  1. Ex-Smoker Says:

    It’s good to know that smoking effects on a child are very small if a mother quits before the 5th month of pregnancy. But nevertheless smoking is bad and this habit is not for wannabe mothers.

  2. James Tilbury Says:

    I agree with the comments above, my biggest issue is that news like will maybe make some women think its safe to smoke during the start of the pregnancy. Its better to QUIT SMOKING as soon as they find out they are pregant or if they are trying for a family, QUIT SMOKING before you even try.

    James Tilbury

  3. Quit smoking Says:

    i’d like to write some words about smoking bans/camp and pregnancy –
    No doubts that there are impact of smoking bans and smoking campaigns as you may see how many people (and pragnents) eventually have realized that smoking is unhealthy. It is good for the long term.
    you may refer to –
    all about smoking facts

  4. Deanne Shuey Says:

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  5. Anh Says:

    Please consult with us next time before doing so.

  6. u14174945 Says:

    The underdevelopment of the foetus during pregnancy is due to lack of prenatal care. when a women is pregnant is essential to look after her self, smoking during pregnancy can cause a loot of complications to the unborn baby, the high levels of carbon dioxide can cause the underdevelopment of lungs in children which can lead to the baby being born severely underweight. according to the women’s health magazine lack of knowledge can be the under one cause of this, most women unknowingly smoke during pregnancy not knowing the effects it may cause on the unborn baby

  7. Hasse Karlgreen Says:

    According to World Heath Report many women do smoking even during pregnancy. It is very harmful for health as well as unborn baby. It causes many disease to mother as well as to child.

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