eli5 Why do some women get “morning sickness” when pregnant and others do not? Why do many only have it in the 1st trimester but some experience their whole pregnancy?
In: Biology
The short version is: the developing fetus makes hormones that make mom feel sick (if mom’s body isn’t used to the hormone).
Hormones are chemical messengers that float around your body and are like snail mail that an organ sends to another organ. For example, when you eat and your stomach gets full, it releases a hormone called leptin. When leptin reaches your brain, your brain gets the “stop eating” message (that’s why it takes 15 or so minutes to feel full after a meal—snail mail, relatively speaking).
It was published a few months ago that a hormone called GDF15 is likely behind morning sickness. One place where GDF15 messages go is to a brain region called the solitary tract, and that brain region controls the gag reflex and vomiting.
People produce different levels of GDF15, depending on genetics, diet, and some other factors. Some people have naturally high GDF15 levels and some have low levels. Fetuses produce a lot of GDF15 it turns out, so it was recently found that pregnant mothers who had low levels of GDF15 before becoming pregnant were more likely to experience morning sickness.
The growing fetus is releasing chemicals that basically push the “vomit button” in mom’s brain, but if mom’s already used to having that button pushed, they aren’t going to be as affected by the fetus. It’s like how a seasoned drinker could hammer back a row of shots without, well, vomiting, whereas someone who’s never had a drink in their life is going to have a bad time doing the same.
Link to study for those interested (definitely not ELI5): [https://www.nature.com/articles/s41586-023-06921-9](https://www.nature.com/articles/s41586-023-06921-9)
edit: 3 words for clarity
Would like to add it’s called morning sickness but you can feel nauseous for the whole entire day or throughout the entire 1st trimester/pregnancy
Latest Answers