NOTTINGHAM (UK) — Nicotine patches in standard dose fail to help pregnant women quit smoking, a large clinical study shows.
“We think our findings are hugely significant. Smoking in pregnancy is the leading preventable cause of morbidity, death and health problems among women and babies. We hope our results will inform future health care policy and guidelines in the field of smoking cessation during pregnancy,” says study leader Tim Coleman, a professor in the University of Nottingham’s UK Centre for Tobacco Control Studies.
“Clearly standard dose nicotine patches do not work in pregnancy as well as they do in the general smoking population. More research is needed; higher dose patches might be effective, but women would also need to be persuaded to use these for longer and research into other ways to help pregnant women give up is also needed,” Coleman adds.
Nicotine replacement therapy (NRT) is proven to be an effective aid for people who want to give up smoking but its effectiveness in pregnant women who metabolize the nicotine more quickly and hence may need high doses for NRT to be effective, has not previously been widely examined. NRT is regularly prescribed to women who are pregnant and advised to quit but there has also been little research to date, into possible adverse effects from nicotine replacement on the mother and unborn child.
The largest-ever randomized trial of nicotine patches in pregnancy was carried out between May 2007 and February 2010. A group of 1,050 women between the ages of 16 and 50 and between 12 to 24 weeks pregnant were recruited from antenatal clinics at seven hospitals in the East Midlands, Stoke and Cheshire. All smoked ten or more cigarettes a day before they were pregnant and five or more cigarettes after they became pregnant.
From the group, 521 women were randomly assigned to eight weeks of nicotine replacement patch therapy and 529 to placebo (visually identical dummy) patches in a double-blind trial to assess the effectiveness and safety of standard-dose therapy of a daily 15 mg/16 hour nicotine patch.
Smoking during pregnancy is a known cause of miscarriage, premature babies, low birth weight, congenital abnormalities and neonatal death. The safety of the nicotine patch therapy during pregnancy was assessed by monitoring for these adverse pregnancy events and birth outcomes.
All the volunteers received support counseling from midwives involved in the research project and agreed to set a quit date within the following two weeks. The women were given a four-week supply of skin patches, either placebo or nicotine, to start on the agreed quit date.
Four weeks after starting therapy the women who had managed to maintain abstinence and passed an exhaled carbon monoxide test were offered another four-week supply. Three telephone counseling sessions were also offered to participants, one on the quit date, one three days later and a third at four weeks. Additional support was also offered from local NHS stop smoking services.
The results of this unique trial showed there was no significant difference in the rate of abstinence between the nicotine replacement and placebo groups from the quit date until delivery of the baby.
The rate of clinically proven and successful abstinence until delivery was 9.4 percent in the nicotine group and 7.6 percent in the placebo group. The researchers deemed this difference non-significant within the metrics of this study.
The proportion of women who managed to adhere to the program was low: only 7.2 percent of women using nicotine patches and 2.8 percent of women using placebo patches adhered to the therapies for more than one month.
The rates of adverse pregnancy events and birth outcomes were similar in the two groups. For singleton births, i.e. not twins, mean birth weight and rates of preterm birth, low birth weight and congenital abnormalities were similar in the two groups. However, although there were significantly more caesarean deliveries in the nicotine group than the placebo one, this is likely to have occurred by chance.
This clinical trial was four times the size of the largest previous study in this area but the results largely mirror the indications set by previous research.
The findings suggest that guidelines for healthcare professionals for smoking cessation in pregnancy should be revisited and should principally encourage the use of patient support methods like behavioral support, which is proven to be effective in helping pregnant women quit smoking.
The research was funded by the National Institute for Health Research Health Technology Assessment (NIHR HTA) program.
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