You might have seen online content claiming that semen or sperm quality causes morning sickness in pregnant women. It’s not true – a man’s semen quality does not cause morning sickness in his partner, and I’m going to explain why.
What is morning sickness?
Morning sickness is the common name for nausea and vomiting during pregnancy. Despite its name, it’s a complication of pregnancy that can occur at any time of the day or night and varies from feelings of nausea to excessive vomiting. Around 70% of pregnant women experience nausea and vomiting in pregnancy.
What causes morning sickness?
For a long time, the cause of nausea and vomiting in pregnancy was unknown but recent research suggests that it’s caused by a rise in the levels of GDF15 (growth differentiation factor 15) in the mother’s blood. GDF15 is known to cause nausea and reduced appetite when levels rise in response to cell damage in the body. In pregnancy, the placenta produces large amounts of GDF15, which is what causes high levels in the mother’s blood. GDF15 is probably important for placental function, and nausea and vomiting in pregnancy might be a side-effect.
The placenta is a magnificent feat of evolution. This temporary organ is produced from scratch by the fusion of tissues from the mother’s uterus and the developing embryo. It provides for nutrition, elimination of waste, gas exchange, growth factors and protection for the developing baby, and is discarded at birth because it’s no longer needed. If another placenta is needed for another pregnancy, a whole new one is grown (and discarded).
The development of the placenta and the baby is affected by the baby’s genes, which are inherited from the mother and father, but the contributions from the mother and father are not equal. There are some genes for which the mother’s or father’s copy predominates, and therefore, the mother’s or the father’s genetic contribution influences development differently for some tissues. For the placenta, there is a slightly greater influence of the father’s genes than the mother’s.
This is where the misinformation comes in
Just because the father’s genes contribute more to the development of the placenta than the mother’s, does not mean that the father’s genes are responsible for the production of GDF15 or nausea and vomiting in pregnancy. The GDF15 gene is not one with different contributions between the mother and father in the placenta.
An interesting thing about GDF15 is that mothers whose levels are low before pregnancy are most likely to have nausea and vomiting in pregnancy. There is no evidence or biological reason for GDF15 levels before pregnancy to be affected by a partner’s semen.
Semen does have GDF15 in it. The prostate secretes GDF15 into the seminal fluid, and it is believed to regulate the immune system during conception, but it does not affect sperm function.
There is no evidence linking semen or sperm to morning sickness, only incorrect beliefs based on a misunderstanding of developmental genetics and placentation.
This doesn’t mean men are off the hook
There are lots of important reasons for looking after yourself to make sure that your sperm are as healthy as possible. Semen abnormalities (e.g. low sperm numbers, lots of misshapen or strangely moving sperm, inflammatory changes or DNA damage to sperm) can reduce fertility, impact on embryo development and growth of the developing baby and cause life-long health issues for offspring.
The importance of semen quality for successful pregnancies means that males have an opportunity, by taking care of themselves, to provide their children with the best start to life. A healthy diet, sufficient physical activity and avoiding things that damage sperm and reduce semen quality (e.g. nicotine, alcohol, infections) are ideal for the health of your future children and to show your commitment to achieving the best reproductive outcomes for you and your partner.
Tim Moss
Healthy Male Health Content Manager
Dr Tim Moss has PhD in physiology and more than 20 years’ experience as a biomedical research scientist. Tim stepped away from his successful academic career at the end of 2019, to apply his skills in turning complicated scientific and medical knowledge into information that all people can use to improve their health and wellbeing. Tim has written for crikey.com and Scientific American’s Observations blog, which is far more interesting than his authorship of over 150 academic publications. He has studied science communication at the Alan Alda Centre for Communicating Science in New York, and at the Department of Biological Engineering Communication Lab at MIT in Boston.
