How to Optimize Fertility in Males & Females

KEYPOINTS

• 01

  Fertility depends on egg and sperm quality, not just quantity

  Both eggs and sperm must shed half their chromosomes through meiosis, ending with 23 single strands. Spindle structures pull the chromosomes apart, and they depend heavily on mitochondria. When separation fails, usually in the egg but sometimes in sperm, the result can be failed fertilization, failed implantation, miscarriage or conditions such as trisomies. That is why many of the tools Huberman covers target mitochondrial health.

• 02

  Monthly odds of conception fall steeply with a woman's age

  With well-timed intercourse, the chance of conceiving in a given cycle is about 20% at 30 or younger, about 18% at 31 to 33, about 11% at 34 to 37, about 5% at 38 to 39, and roughly 1 to 3% after 40. Common OB-GYN advice is to try for about six months under 30 and nine months to a year in the mid-30s before seeking help. At 38 or older, Huberman suggests seeing a doctor at the outset.

• 03

  Miscarriage risk also rises with egg age

  About 25% of fertilizations in women 35 and older end in miscarriage, rising to about 50% by the early 40s. A common reason is chromosomal error when the egg ejects half its chromosomes in the polar body, leaving extra or missing chromosomes so the embryo cannot develop normally. Miscarriage can also arise from sperm or the uterine environment.

• 04

  Know your reserve early: AMH and antral follicle counts

  Each month a cohort of small antral follicles, about 2 to 9 mm, leaves the ovarian reserve. An ultrasound count across both ovaries (often 20 to 40 in a woman's 20s or 30s) and a blood test for anti-Müllerian hormone give a window into remaining eggs. Both decline over time. Huberman relays OB-GYNs' advice to measure several times, and earlier than most women do.

• 05

  Men should get a semen analysis, roughly every five years

  After 48 to 72 hours of abstinence, clinicians look for about 2 to 5 mL of ejaculate, a concentration of at least 15 to 20 million sperm per mL, and ideally 60% or more motile sperm. Normal-looking volume can contain few or no sperm. The urologists Huberman consulted recommend testing every five years and considering freezing sperm young, since paternal age is linked to some developmental risks, though absolute risk stays relatively low.

• 06

  Heat is the enemy of sperm

  Sperm take roughly 60 to 90 days to develop, so heat exposure affects a full cycle. The cremaster muscle raises or lowers the testes to regulate temperature, so boxers versus briefs makes little difference. Hot tubs, hot baths, saunas without a cold pack, long sitting, heated car seats and large thighs from fat or muscle can raise scrotal temperature.

• 07

  Phones in front pockets may reduce sperm quality

  Huberman cites a meta-analysis of 18 studies and 4,280 samples linking mobile phone use with lower sperm quality, through both radiofrequency and heat effects and regardless of usage time. He calls it likely one contributor, not the whole explanation, and advises keeping the phone away from the groin.

• 08

  Alcohol, smoking and stress all impair fertility

  Smoking damages egg spindles and mitochondria and raises reactive oxygen species in semen; that includes cannabis and vaping. A single binge of five or six drinks can affect sperm for the whole 60-to-90-day production window and the entire monthly cohort of follicles, partly by disrupting GnRH release in the hypothalamus. Huberman advises no alcohol while trying to conceive or pregnant, prioritizing sleep and keeping cortisol earlier in the day.

• 09

  Infections and testosterone therapy can quietly lower fertility

  Chlamydia often causes no symptoms yet raises the risk of ectopic pregnancy and miscarriage, so fertility clinics test for STIs. A significant viral illness in the prior 70 to 90 days can lower sperm count and quality. Testosterone replacement suppresses LH and FSH and can drastically cut sperm production unless offset, for example with hCG, FSH or clomiphene under a urologist's or endocrinologist's care. Supplements like tongkat ali, at normal doses, should not suppress natural testosterone.