Behind the Headlines

Friday October 30 2009

“Women undergoing fertility treatment with artificial insemination may boost their chances of pregnancy if they lie still afterwards,” the BBC has reported.

These findings come from a Dutch study of 391 couples who were treated for conception problems. The researchers asked the women to lie down for 15 minutes or get up immediately after having sperm inserted directly into their uterus (intrauterine insemination). It found that 27% of the women who lay down after insemination went on to have a baby, compared with 17% of women who got up and moved around. This study used a robust design to investigate the effects of lying down (immobilisation) after intrauterine insemination. The study had other strengths, including a relatively large number of participants and the fact that all the participants were followed up. This increases the likelihood that the results are reliable.

An accompanying editorial article on the research reported that there were lower pregnancy rates in this study than in other centres that do not use immobilisation. This could be because different centres use different techniques, or because patients’ fertility problems have different causes. This study promotes the potential benefits of lying down after insemination, and may encourage centres that do not already do so to try this practice.

 

Where did the story come from?

Dr Inge Custers and colleagues from the Academic Medical Centre and other medical centres in the Netherlands carried out this research. The study received no external funding and was published in the peer-reviewed British Medical Journal.

 

What kind of scientific study was this?

This was a randomised controlled trial that looked at whether lying down for 15 minutes after intrauterine insemination improved rates of pregnancy, compared with moving around immediately after the procedure.

The researchers enrolled 391 couples who were eligible to have intrauterine insemination because they were subfertile (having problems conceiving). These couples attended seven different hospitals in the Netherlands. They had received thorough medical investigation, which found that the cause of their subfertility could not be identified, was due to problems with the woman’s cervix or was the result of male subfertility. The women in these couples were aged between 18 and 43.

The researchers randomly assigned the couples to either the group that would remain lying down or the immediate mobilisation group. Intrauterine insemination involved obtaining a sperm sample from the male partner (in a minority of cases, donor sperm was used) and injecting it directly into the uterus to increase the likelihood of conception. In some cases, women received drugs in advance of insemination to stimulate egg production. Couples received up to three cycles of insemination.

If the women had not started their period within two weeks of insemination, they took a pregnancy test to see if they had become pregnant. The researchers confirmed that pregnancy was progressing by using ultrasound to look for a foetal heartbeat at 12 weeks of pregnancy. If a heartbeat was found, the pregnancy was described as “ongoing”. The researchers also looked at whether any women had ectopic pregnancies or miscarriages, and how many went on to deliver live babies.

 

What were the results of the study?

The couples received an average of 2.4 cycles of insemination in the lying down group, and 2.5 cycles in the immediate mobilisation group. The researchers found that lying down for 15 minutes after insemination increased the proportion of couples who achieved an ongoing pregnancy (27%) compared with immediate mobilisation (18%). This represented an increase of 50% in the chances of an ongoing pregnancy (relative risk 1.5, 95% confidence interval 1.1 to 2.2).

Lying down after insemination reduced the time it took to achieve an ongoing pregnancy. The women in the lying down group also had a higher rate of live births, with 27% having a live birth compared with 17% in the immediate mobilisation group.

Ten of the pregnancies did not occur through artificial insemination, nine occurred naturally between treatment cycles and one woman became pregnant after she began receiving IVF (in-vitro fertilisation) during the study. When the researchers excluded these pregnancies from their analysis, it did not affect the results.

 

What interpretations did the researchers draw from these results?

The researchers concluded that lying down for 15 minutes after intrauterine insemination increases pregnancy rates compared with moving around immediately afterwards. They suggest that “immobilisation for 15 minutes should be offered to all women treated with intrauterine insemination.”

 

What does the NHS Knowledge Service make of this study?

This study used a robust design to investigate the effects of immobilisation after intrauterine insemination. The study had other strengths, including a relatively large sample and no loss to follow-up. This increases the likelihood that results are reliable. There are a few points to note:

  • There was some variation between the methods used by the hospitals involved, and centres using different methods may have differing success rates.
  • An accompanying editorial to the study suggests that the study had lower pregnancy rates than other centres that do not use immobilisation. This could be due to differences in the techniques used or the types of subfertility treated.
  • It is not possible to tell from the study what length of lying down produces the best results.
  • This study cannot tell to what extent lying down after intercourse might improve pregnancy rates for people trying to conceive.

Some centres treating subfertility may already include a period of lying down after insemination. This study promotes this and may encourage other centres to try this practice.

Analysis by Bazian

Edited by NHS Choices

Links to the headlines

'Lie still' for pregnancy boost. BBC News, October 30 2008

Lying down after insemination boosts pregnancy chance: research. The Daily Telegraph, October 30 2009

Trying for a baby? Let gravity do the work. The Independent, October 30 2009

Links to the science

Custers IM, Flierman PA, Maas P et al. Immobilisation versus immediate mobilisation after intrauterine insemination: randomised controlled trial. BMJ 2009; 339:b4080

Editorial:
Supine positioning after intrauterine insemination

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