Getting an Infection during the period of "Morning Sickness", poses Higher Risks of Congenital Heart Disease?
One of the most unexpected parts of the conversation was Jimmy Carr’s discussion of morning sickness. 🫣
It sent me down a rabbit hole because there is an interesting evolutionary theory behind why morning sickness tends to occur during this particular period of pregnancy.
The Maternal and Embryo Protection Hypothesis, an evolutionary theory about morning sickness, where:
Organogenesis: Morning sickness typically peaks between weeks 6 and 14 of pregnancy. When the embryo’s major organs (including the heart, brain, and limbs) are forming and are most vulnerable to damage from toxins or pathogens.
The "Shield" Effect: Because pregnancy naturally suppresses a woman's immune system (to prevent her body from rejecting the fetus), she becomes more sensitive to foodborne pathogens. Evolutionary biologists believe nausea and vomiting evolved to force mothers to avoid or expel potentially toxic or bacteria-laden foods during this window.
The Shift: Once the organs are fully formed (around the second trimester) and the baby enters the growth-only phase, morning sickness usually stops for most women.
EVIDENCE for Infection & Congenital Heart Disease ﮩ٨ـﮩﮩ٨ـ🫀ﮩ٨ـﮩﮩ٨ـ
A link from two meta-analyses, between First Trimester Maternal Infections and Fetal Congenital Heart Defects has been found, especially in regards to rubella virus, coxsackievirus, respiratory infections, and influenza.
⚠️ Though there is an important distinction here to make:
This does NOT mean that morning sickness itself is linked to congenital heart defects.
But the same period of pregnancy in which morning sickness may have evolved to reduce exposure to potentially harmful substances is also a period when the developing embryo is particularly vulnerable to certain environmental insults, including infections.
