Recent research has suggested that taking Paracetamol (acetaminophen) during pregnancy for long periods of time may lower testosterone production in the male fetus – potentially increasing the risk for undescended testes and adverse reproductive health effects later in life.
The animal study published in the journal Science Translational Medicine (STM) investigated the effects of Paracetamol exposure on fetal testosterone levels. The researchers, from the University of Edinburgh, used host mice grafted with human fetal testicular tissue to study the effects of Paracetamol on testosterone production. The grafted testicular tissue simulated the developing testes during pregnancy.
The researchers found a 45% decline in plasma testosterone levels after 7 days of exposure to a typical dose of acetaminophen. However, after one day of exposure to a typical dose there was no change in testosterone levels.
A 2010 study published in the journal Epidemiology linked protracted use of Paracetamol during pregnancy to undescended testes (cryptorchidism) in males; however, the University of Edinburgh study was the first to demonstrate the effects of the drug on testosterone levels.
“These results are of clinical importance as there is growing evidence that most common male reproductive disorders, which can affect 1 in 6 men, may be attributed to sub-optimal testosterone exposure during fetal life,” the authors wrote.
What is testosterone?
Testosterone, a sex hormone, is produced by the testes in approximately the 7th or 8th week of pregnancy. Testosterone has key effects on sex drive, bone mass, the growth of body hair, fat distribution, muscle strength, brain function, metabolism, the vasculature and the production of sperm.
Testosterone is important to the developing fetus because it determines the sex of the newborn as well as future reproductive health.
Health implications of lowered testosterone in the womb
Researchers have suggested that reduced levels of testosterone in the womb may have implications later in life.
According to the authors of a reproductive health study published in the journal Proceeding of the National Academy of Science, during the period of fetal masculinization, testosterone exposure can (re) program fetal stem cells which later develop into testosterone producing adult Leydig cells. A lower testosterone exposure in the fetus can lead to lower
testosterone levels in the adult male which can ultimately impact fertility, erectile function, and sex drive.
Past research has previously linked low testosterone in adult males to an increased risk of other health issues such as obesity, depression and type 2 diabetes.
Paracetamol (acetaminophen) safety during pregnancy
According to the authors of an American Family Physician journal article, acetaminophen has a good safety record and is widely used during pregnancy with a paucity of adverse effects documented; hence, why acetaminophen has been validated as the pain reliever of choice during pregnancy.
An article published in the journal JAMA Pediatrics, suggests the safety record is less clear. The authors associated the use of acetaminophen during pregnancy to a higher risk of ADHD and other hyperactivity behavior disorders in children, with the risk stronger for maternal acetaminophen use in more than 1 trimester.
As both an over the counter and prescribed medication, Paracetamol is one of the most commonly used analgesic (pain) and fever medications used during pregnancy
A 2005 study published in the American Journal of Obstetrics and Gynecology reported at least 65% of women had used acetaminophen at one point or another during their pregnancy.
Planning a pregnancy?
This recent study also highlights the public health relevance of medication effects during pregnancy. Women who are planning a pregnancy or have just learned they are pregnant should consult with their physicians prior to taking any prescribed or over-the-counter medications.