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Old 10-10-2012, 09:04 AM   #33
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Join Date: Sep 2010
Location: San Antonio
Posts: 692
Re: Going pat 41 weeks...really dangerous?

I was actually researching this just the other day. The conclusion I was seeing was that inducing at 41 weeks vs 42 improves outcomes...BUT here's the thing: the rate of still birth at 40 weeks is 4 in 1000. If you wait until 42 weeks, the rate of still birth nearly 7 in 1000. And yeah, that sounds scary, but here's the thing. Put it into percentages: 4/1000 = 0.004 = 0.4%; 7/1000 = 0.007 = 0.7% Now, flip that worst, there is a 99.3% chance of your baby NOT dying. It is a small risk.

This is a good (if dense) read: It's a meta-analysis of studies, which means it has done the number crunching for you. A few relevant bits:

* The risk of antepartum stillbirth increases with increasing gestational age. Data from several large studies in the United Kingdom show that, when calculated as deaths per 1,000 ongoing pregnancies, antepartum stillbirth rates begin increasing after 40 weeks, with estimates of 0.86-1.08/1,000 between 40 and 41 weeks, 1.2-1.27/1,000 between 41 and 42 weeks, 1.3-1.9/1,000 between 42 and 43 weeks, and 1.58-6.3/1,000 after 43 weeks.

*Although not statistically significant in most individual trials, there is a consistent finding that perinatal mortality rates are lower with planned induction at 41 weeks or later compared with expectant management, a finding confirmed by formal meta-analysis. Based on the observed absolute risk difference in the meta-analysis, at least 500 inductions are necessary to prevent one perinatal death. Whether this is an acceptable trade-off at either the policy or individual level is unclear.

*There is a remarkable lack of data on patient-oriented outcomes, such as quality of life or measures of patient preferences for different outcomes or for different processes to achieve those outcomes.
Here's another quote from a different part of the article which is also relevant (note the numbers given here are different than what I mentioned earlier, and what I found last time I looked into this, but the conclusion drawn is the same):

In some cases, these risks appear to be due to uteroplacental insufficiency, resulting in eventual fetal hypoxia. Data from large registries show that the risk of perinatal death, especially of antepartum stillbirth, increases with advancing gestational age. If risk is calculated based on the number of ongoing pregnancies, gestational-age-specific stillbirth risk reaches a nadir at 37-38 weeks and then begins to increase slowly. Risks increase substantially after 41 weeks; however, the absolute risk is still low (between 1 and 2 per 1,000 ongoing pregnancies between 41 and 43 weeks).
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