Study: Risk of Stillbirth Week by Week (late third trimester)

[finsmum]

The policy of inducing at 41 or 41 plus3 weeks came from data from a 1963 study suggesting that the risk of stillbirth doubled from 1% to 2% between 40 and 42 weeks. This is what medical practice and advice is based on, but clearly the information is outdated.

The study above is not the only one to show that birth at 42 and even 43 weeks actually carries less risk than at 37 or 38 weeks (and we're told that 37 weeks is full term! It is, but only for some babies). There are also studies showing that the average length of pregnancy, especially for first timers, is at least 8 days longer thsn 40 weeks (eg Mittendorf et al, 1990). The 40 week thing is based on miscalculations in the 1700's from a bible passage, believe it or not!!

Wish I'd known all this before I agreed to an induction at 42 weeks, to deliver, via ventouse after a harrowing and agonising Sintocinon birth, my perfect but tiny and vernix covered daughter, to hear the midwife say, 'oh, she looks a bit premmie! Looks like she could have done with a few more weeks in there".....!!!!!!!!

Thanks, Kelly, for bringing this study to light!

[onthefly]

Some interesting thoughts, thanks.
My OB said he was concerned about going past 42 weeks as the risk of stillbirth increased significantly. I had also heard this from midwives.
But, I also read something referencing a study that the average gestation for first-time mums was about 41+3 or something like that. (maybe it was the same study you refer to finsmum)

I wonder how much of this is psychological - when a baby is stillborn at 42 weeks, the natural reaction is to think "Well if we'd delivered earlier, this wouldn't have happened"...

[BellyBelly]

Thats been said by various studies tho, from: Naturally Inducing Labour - Natural Induction Methods

According to a study on ‘The length of uncomplicated human gestation’ by the Department of Epidemiology, Harvard School of Public Health in Boston, Massachusetts, they found:

“For primiparas (first child), the median duration of gestation from assumed ovulation to delivery was 274 days, significantly longer than the predicted 266 days. For multiparas (more than one child), the median duration of pregnancy was 269 days, also significantly longer than the prediction. Moreover, the median length of pregnancy in primiparas proved to be significantly longer than that for multiparas”

[Glamourcide]

Or... just thinking out loud here...
Does the risk of stillbirth only appear to decrease because so few babies are 'allowed' to go so far? Obviously induction of post-date babies is quite common, I can't help but think perhaps the studies are flawed because the vast majority of doctors do suggest and the (usually sick of being pregnant by that stage) mother accepts an induction within a week or so of going past the EDD? So if nobody was induced for going post-dates, would the rate of stillbirths in 41w+ babies then increase because the risk IS there but hardly anybody actually ever gets to 42+ weeks to find out, kwim?

ETA: From my own experience, I would be very reluctant to allow myself to go past 41w. DD1 was induced at 39+5 and her placenta was gorgeous and healthy, but DD2 went to 40+7 and her placenta was pretty much dead - nothing had been picked up but I knew the minute I saw it, and the midwife confirmed, that if I hadn't been booked in for an induction for the very next day (I went into labour spontaneously), chances are she would either have not made it another 24 hours, or would have come very, very, very close because the placenta was so badly deteriorated. Just my experience, obviously, but something I'd be very wary of if I were planning any more babies.

[BellyBelly]

Given that it's a ratio type of result and the way they worded how they worked out the figures, I would assume it would be out of babies born at that week. So if 500 babies were born at 42 weeks, then they would work out a ratio dependent on the stillbirths x:500

[onthefly]

I understand what you mean Glamourcide. For me, my placenta was absolutely wonderful at 42 weeks, so I'd feel fine going longer now.

[edaj84]

Marcellus, I know exactly what you mean. My placenta looked absolutely perfect and healthy, as did my baby that was covered in vernix at 43w+5d