# "low pressure storms" induce labor in pregnant women?

This claim was implied on tonight’s ABC World News Tonight. Assuming there is some truth to the claim – *and please tell me if there isn’t * – what is the operative term in the statement, “low pressure” or “storm.”

Is there something about a pregnant woman that is akin to a bottle of champagne? Lower the ambient air pressure enough, and out pops the kid?

Or maybe the reporter meant that a traumatic event, like a hurricane, can excite mothers-to-be so much that they will self-induce labor.

What do you guys make of his statement?

Stress can induce labor (if it occurs early enough in the pregnancy, it’s called a miscarriage). Not all stress induces labor, but the greater the stress the greater the odds of such a thing occuring.

As an example, having your house collapse around you in a hurricane would qualify as a very high-stress situation and stands a very good chance of causing a pregnant woman to go into labor, particularly if she is near her due-date anyway.

Various disasters, both natural and man-made, as well as extreme emotional stress can have that effect.

I was all set to do the calculations and call this utter B.S., but it seems that a large drop in atmospheric pressure would actually exert quite a powerful force.

The highest barometric pressure is about 108 kPa, the lowest about 88 kPa.

A 20 kPa difference in pressure acting over a 0.01 m[sup]2[/sup] area (10 cm dilation on a square vagina) would equal a force of 200 Newtons, or the amount of force required to lift a 20 kg object. I assume that typically the pressure change from normal to storm is more on the order of 5-10 kPa, and for people with round birth canals the area might be 50% of what I quotes, but that’s still 20-100 Newtons of force! :eek:

How this compares to the force required to push out a baby is … for someone more qualified to discuss.

From an article on the subject:

Seem like this would be pretty easy to test in a lab. Get 100 40-weeks-pregnant women in a test room, 100 in a control room, and drop the air pressure in the test room.

I’m sensing a federal research grant here…

If there were a bladder of air inside the pregnant woman, this would be a more persuasive argument.

And the theory that a reduction in pressure induces childbirth is quite incomplete without looking at what happens when pregnant women travel on airplanes or drive into mountainous areas, as these pressure changes are far greater than those associated with storms.

This is totally anecdotal, but when I was in hospital in Japan having my second baby, I was there for three months. There were three typhoons and on each occasion a rush of births resulting in us Mums in waiting being shifted to different rooms or floors in order to free up bed space near the birthing suites. The nurses were always extra rushed and they all commented that typhoons will precipitate births. I presume for the women almost ready to pop, it just tips them over the edge.

Only a story, but I did see the rush and the new babies.