A couple has been trying to conceive for 9 months. Which factor is most likely to affect their ability to conceive?

The use of lubricants with each sexual encounter can significantly impact a couple's ability to conceive, particularly if the lubricants contain ingredients that are harmful to sperm. Many commercial lubricants may have spermicidal properties or alter the pH balance, making the environment less conducive for sperm survival and movement. Some lubricants can also create a physical barrier, further complicating the natural process of conception.

In contrast, factors such as an exercise regimen, frequency of intercourse, and menstrual cycle length can influence fertility, but none are as directly impactful on sperm viability and motility as the type of lubricant used during sexual activity. For optimal fertility, it's advisable for couples trying to conceive to use fertility-friendly lubricants or to avoid lubricants altogether if possible, to create an environment that supports sperm health and mobility.