Sick of Pregnancy? You Could Be Having A Girl
A key word there is "speculation". Askling made it clear that their "hypothesis does not rest on firm ground." But it does perhaps lay the groundwork for future studies. "I think that's how one should look at our results. Our results don't clear the mist and show a big sequence of events, but they add an extra piece of information or some extra knowledge about what is going on in early pregnancy," Askling tells WebMD.
Askling and colleagues write that an important limitation to the study is the lack of specific knowledge about what caused the women to become sick. "Non-medical factors may contribute to hospital admission," according to the researchers.
So, should women start thinking 'sugar and spice' when they're feeling anything but nice? "This by no means is a way for the individual couple to determine the sex of their offspring. This is purely a statistical phenomenon that can only be proved or shown in large groups," Askling tells WebMD. "We've studied a million births, where a number of thousands of women had this very severe morning sickness. So, we have studied women at one end of the spectrum. Extrapolating from there, to an individual expectant woman, would be stupid, and you cannot really do that, and as illustrated by our study, almost half of the women with severe nausea did eventually give birth to boys, so the predictive value of this, for the individual mother, is not much better than tossing a coin."
Sharon Phelan, MD, an associate professor at the University of Alabama at Birmingham, mentioned some of the same limitations Askling did. She says the accuracy of the diagnosis about the woman's severe morning sickness "creates additional confusion" because the definition of hyperemesis isn't "straightfoward".
Phelan says she doesn't know if the study has "an adequate sample size to make that conclusion" because although there were one million births, the speculation is based on about 5,900 pregnant women. Then there are the odds: "He [the researcher] is saying it's 56 to 44, and those are almost 50-50 odds, it's not that different."