Does caffeine, like smoking, lower your chances of getting pregnant?
There is conflicting evidence on this, said Dr Loh Seong Feei, medical director of Thomson Fertility Centre.
A multi-centre European study published in 1997 found that women who consumed 500mg of caffeine or more daily took a longer time to get pregnant. The authors concluded that high levels of caffeine might delay conception, said Dr Loh.
But a review of studies from 2000 to 2009 found that caffeine consumption did not seem to affect fertility, sperm quality and success rates of in-vitro fertilisation (IVF).
What is very clear, though, is that smoking lowers your chances of getting pregnant.
"Smoking has consistently been proven to affect various aspects of human fertility, including egg reserves, sperm quality and IVF pregnancy rates," said Dr Loh.
In the light of the initial 1997 study, doctors still generally advise women who want to get pregnant to reduce their consumption of coffee to one or two cups a day, said Dr Loh.
A version of this article appeared in The Straits Times.