Of the media who reported this study probably the least sensationalist and best summary of the research was one by Honor Whiteman writing for medical news today
In a nutshell this study reported a controlled experiment of 29 well pregnant women who were monitored in different positions for 30 minute periods during the day. In this ground breaking study they avoided ‘high risk’ women with comorbidities and also did not monitor their participants during sleep. In doing so they had probably as clean a look as is currently possible at the human fetus’ response to the maternal supine position when compared to the same fetus spending the same time with the mother lying in other positions.
It is very interesting that they found an increased likelihood of fetal quiescence in the supine position especially as this was in a group of normal healthy late third trimester pregnancies. As they say, this finding suggests that the well fetus is able to mount an adaptive response to this potential stressor by shifting to a lower oxygen consuming state. If they have found this in the well fetus, during a 30 minute period in the supine position, with the mother awake, one can only speculate as to what might occur in a vulnerable fetus, whose mother is sleeping supine for several hours during the night.
Professor Stone concludes his study by saying “The supine position maybe disadvantageous for fetal wellbeing and in compromised pregnancies may be a sufficient stressor to contribute to fetal demise.” He also says that now they have found this during the day that the next logical step is to monitor women at night.
This study lends weight to the four epidemiological studies published to date that have all reported significant increased risk of stillbirth associated with the supine sleep position. It is therefore disappointing that some of the other stories reporting this study have kind of missed the point.
For example a live science story asks Does Lying on Your Back During Pregnancy Increase Stillbirth Risk? and suggests that some unnamed “experts” say that it's too early to make recommendations based on the findings from this study, and that pregnant women do not need to change the way they lie down as a result of the study. This misses the point because the study wasn’t actually looking at risk for stillbirth, per se but simply set out to show what happens to a well fetus when the mother lies on her back. Then the live science report goes on to say
- "It is not possible to draw a firm link between maternal position and stillbirth risk from this study and further robust research is needed," Hannah Knight, a spokesperson for the Royal College of Obstetricians and Gynaecologists in the United Kingdom, said in a statement. "Women should sleep in a position that is comfortable for them," Knight said.
- “It is important that women are not unnecessarily alarmed by the results of this small study of 29 women, none of whom had a stillbirth," Knight said. She also noted that the study measured the occurrence of a sleep-like state in the fetuses, "which has little evidence of any association with hypoxia, brain damage or stillbirth."
The UK Sun also reported the study with a sensational headline PREGNANCY PERIL Mums-to-be warned that sleeping on back can seriously ‘increase risk of stillbirth’ : Even reclining on the sofa for half-an-hour could be dangerous to unborn babies, researchers warn
This report kinda gets it wrong too by overstating, or wrongly stating what the study actually found eg
- It follows a study that found lying back can reduce oxygen supply to babies in the womb.
- The biggest danger period seems to be the last three months of pregnancy.
- New Zealand scientists found babies’ heart rates and oxygen supplies dropped when expectant mums lay flat on their back just for 30 minutes.
So what now? Well to be frank I’m excited. Excited that we have a well conducted study that has added an important piece of the puzzle to what we already know. That is: sleeping on your back in late pregnancy is probably not a good idea and is best avoided by asking pregnant women to settle to sleep on their side.