If you’re in the trying to conceive (TTC) club, you know that timing can be well, kind of everything. Curious about the best time of day to get pregnant—not just the best time of month? Researchers are one step ahead of you.
Many couples focus on the time of the month when trying to get pregnant. But the time of day could be just as important—if not more so.
Recent research suggests that the best time to try to conceive is before 7:30 a.m. That’s when male sperm concentrations are higher. (More sperm equals more chances for one to meet up with an egg.)
Why is there more sperm in your guy in the morning? When men sleep, their bodies regenerate sperm lost during the day. Having sex earlier in the day could be your best bet, research shows.
The study on 12,245 semen samples from more than 7,000 men found that sperm concentration, count and size and shape were highest around the 7:30 a.m. mark. There weren’t any changes in progressive motility, which is when they swim in a straight line or large circles.
Higher concentrations and counts occurred in the spring, but they dropped off during the summer months. Semen quality differs based on a man’s circadian (daily) and circannual (annual) rhythms. Authors of the study say taking semen samples early could be used to improve natural and assisted fertility.
What factors affect men’s sperm?
Other research has shown that sleep behaviors can have an impact on sperm count.
Genetics play a role, too. Studies have shown that the genetic makeup of clock genes are associated with semen parameters and the risk of infertility, explains Jane L. Frederick, MD, a fertility doctor with HRC Fertility in California.
In other words, “different times of the day might affect total sperm count, sperm motility or normal morphology in men, and subsequently impact their fertility,” Frederick tells Motherly.
Here’s how important circadian rhythms (as well as good quality and regular sleep) are for male fertility: In studies on male mice, when the gene for circadian rhythm is knocked out, the mice were infertile. Dr. Frederick says this is probably because of abnormal hormone secretion, small testes and seminal vesicles, and low sperm count.
Sperm quality and numbers vary daily for all men, but working irregular schedules may affect it even more. “Those who work irregular shifts exhibit compromised fertility and lower sperm density, motile count and testosterone,” she says.
Fecundability (get familiar, TTCers, you’re about to hear this one a lot along your journey), the likelihood that you’ll get pregnant in a single month (or menstrual cycle), is different among age groups in men and women. But how long you sleep, the timing of when you sleep, and working night shifts weren’t linked to fecundability or odds of live birth in women who experienced pregnancy loss, according to a recent study.
(That’s not to say that sleep doesn’t affect fertility—there’s a lot of research indicating that poor sleep can impact your ability to conceive.)
Dr. Frederick agrees that semen in the early morning (before 7:30 a.m.) has the highest sperm concentration, total sperm count and normal morphology compared to the other times of the day.
“Fluctuation in testosterone production is affected not only by the rhythmic genes expressed in the testicles, but also by circadian rhythms throughout the body,” she says.
A more robust study is needed to confidently show the circadian patterns of sperm parameters.
When’s the best time to conceive?
There’s nothing really set in stone in terms of the time of day that’s best to go for it—just some research that could point you in the right direction. (But again, no guarantees.) Yet, knowing what time of day and month are optimal may increase your chances… we just don’t have the studies to prove it yet.
The time of day may not be the only timing to pay attention to. Some research has shown better fertility rates according to season—that aligns with the aforementioned research. Studies that have shown better fertility in the spring compared to the winter indicate that sperm parameters change with the seasons, Dr. Frederick says.
In terms of current research, there’s not much more available in terms of saying that early morning sperm could increase your chances of getting pregnant. Certainly, timing sex with ovulation (as well as with other factors) plays a pivotal role as well.
Jane L. Frederick, MD, is a reproductive endocrinologist with HRC Fertility in California.
Freeman J, et al. Preconception sleep duration, sleep timing, and shift work in association with fecundability and live birth among women with a history of pregnancy loss. 2022. Fertility and Sterility. doi:10.1016/j.fertnstert.2022.10.026
Levitas E, et al. Seasonal variations of human sperm cells among 6455 semen samples: a plausible explanation of a seasonal birth pattern. 2013. Research Reproductive Endocrinology and Infertility. doi:10.1016/j.ajog.2013.02.010
Kloss J, et al. Sleep, sleep disturbance, and fertility in women. 2015. Sleep Medicine Reviews. doi:10.1016/j.smrv.2014.10.005
Wang Y, et al. Sleep behavior is associated with over two-fold decrease of sperm count in a chronotype-specific pattern: path analysis of 667 young men in the MARHCS study. 2021. Chronobiology International. doi:10.1080/07420528.2021.1896534
Wilcox A, et al. The timing of the “fertile window” in the menstrual cycle: day specific estimates from a prospective study. BMJ. 2000. doi:10.1136/bmj.321.7271.1259
Xie M, et al. Diurnal and seasonal changes in semen quality of men in subfertile partnerships. 2018. Chronobiology International. doi:10.1080/07420528.2018.1483942