Just curious if you have seen research on what you have mentioned regarding duration of valsalva in pregnant women who have had prior training history and more specifically the body adapting to handle pressure changes which would show no danger for pregnant women.
I haven't seen anything specifically on either the valsalva and pregnant women or IAP and pregnancy but as with most topics you don't need specifics to make reasonable and educated conclusions. There's quite a bit of evidence to suggest that under normal coniditions (good mechanics, prior experience, nothing excessive, adequate nutrition) heavy lifting is safe for pregnant women. Here's a couple references:
- Ahlborg G Jr, Bodin L, Hogstedt C. (1990). Heavy lifting during pregnancy–a hazard to the fetus? A prospective study. Int J Epidemiol, 19(1):90-7.
- Wergeland E, Strand K, Bordahl PE. (1998). Strenuous working conditions and birthweight. Acta Obstet Gynecol Scand.,77(3):263-71.
- Klebanoff MA, Shiono PH, Carey JC. (1990). The effect of physical activity during pregnancy on preterm delivery and birth weight. Am J Obstet Gynecol., 163(5 Pt 1):1450-6.
As for pressure changes I was looking for (but unable to track down) a series of articles I have that looked at the IAP of elite power lifters who had IAP readings that were off the charts and had no adverse affects. The IAP readings were 2-3x what a normal person could handle. The conclusion was that they had adapted to produce more and handle more IAP. I believe the articles may be in my work office. I'll see if I can find them when I go back.