Poor fetal growth and maternal smoking reduce sperm quality, finds study

BMJ 2013; 347 doi: (Published 08 July 2013) Cite this as: BMJ 2013;347:f4416
  1. Zosia Kmietowicz
  1. 1BMJ

Researchers have found that the quality of early life in the womb, especially fetal growth and whether the mother smoked, has an important effect later on young men’s testicular health.

The team, from Perth, Australia, looked at the testicular volume, semen quality, hormone production, and body fat composition in 423 men aged 22 and 23 years born to a cohort of 2900 mothers enrolled in a study during their pregnancy in 1989-91 (the Western Australia pregnancy (Raine) cohort (

They found that around one in six men had sperm characteristics below what would be considered normal under World Health Organization definitions. For example, 15% of the men had a sperm volume of less than 1.5 ml, 19% had a total sperm count of less than 39 million, and 14% had sperm with less than 32% motility. In addition, a quarter (26%) had abnormal sperm morphology.

When researchers compared these findings with information they collected on the men in utero and in early childhood, they found that those who were consistently small in utero were significantly more likely to have a sperm assessment in the lowest quarter of all the men assessed. Having a mother who smoked during pregnancy was also associated with lower sperm production (P=0.046), while testicular volume was correlated with child growth (P=0.001), height (P<0.001), and total lean body mass (P<0.001).

The findings were presented at the annual meeting of the European Society of Human Reproduction and Embryology in London on 8 July.

Roger Hart, professor of reproductive medicine at the University of Western Australia who led the study, said that although it is widely believed that sperm counts were falling, it was very difficult to state this categorically.

“Study recruits [in general] may be partners of women undergoing IVF treatment, men volunteering to become sperm donors, male partners of women attending antenatal clinics, men prior to a vasectomy operation, or healthy conscripts to the army. This makes deriving the semen report of an ‘average’ man within a large population very difficult.”

He added, “The main message from the study is that to reach adulthood with the best possible testicular function, a man should not be exposed to his mother’s smoking, should have good fetal growth and, in childhood and through adolescence, should be ‘appropriately grown’—that is, neither underweight nor overweight—and as an adult should not smoke or take drugs.”

Commenting on the study at a press briefing before the conference, Allan Pacey, senior lecturer in andrology at Sheffield University, said that the study confirmed what researchers suspected. “A man’s sperm count depends on what happened in the womb and how those testicles developed. It is a nice hypothesis, and there is growing evidence to support it,” he said.


Cite this as: BMJ 2013;347:f4416