[uniformlyrandom]

I had to skim the article to make sure you were not kidding. In retrospect, this is not so unusual - this was a rescue operation, so regular no-flying constraints did not apply. And normally, ~4% of women are pregnant, so EV for number of pregnant and ready to give birth women is 10860.04(percentarge pregnant)0.5(percentage of women)/9(only 9-month pregnant are ready to give birth) ~= 2.41. What surprising is that they gave birth during the flight, and not on any other day of the month. TRansition from danger to relative safety, I guess?

[whatever_dude]

A rescue operation probably prioritized "women and children first" so I'd assume there's a higher likelihood of pregnant women in flight, therefore higher likelihood of births.

[FabHK]

Yes, so if time of birth is uniformly random (haha) across the final month, then, assuming the flight took, say, half a day, you'd still have to multiply by 0.5/30, so have only ~0.05 expected child births. Still surprising, in other words. Good chance pregnant women were prioritised.

[tzs]

It was also probably a stressful and frightening flight. A lot of people believe that this can increase the chances that a woman will go into labor [1], although a quick round of Googling didn't turn up anything convincing on whether or not that is true or just a myth.

[1] https://www.youtube.com/watch?v=RyRrz9Soutw

[Banthum]

I feel fairly comfortable saying that in a group of Ethiopians in 1991, probably more than 4% are pregnant. For comparison, I've read that 10% of Syrian women in the refugee camps were pregnant at any given time. Doing the math (with world bank stats):

Ethiopia fertility 1991: 7.2

Ethiopia female life expectancy 1991: 49

Total pregnancy time: 7.2 * 0.75 years = 5.4 years

Lifespan proportion spent pregnant: 5.4 / 49 = 11%

[nly]

Maybe they evacuated a maternity unit.

[avip]

500 women in age give ~10 birth/year. Probability of birth in a given day is therefore 100 * (1 - (364 / 365.0) ^ 10) ~ 3%

[mesofile]

and/or change in atmospheric pressure?