How To Optimize Fertility In Both Males & Females (Part 1) | Huberman Lab

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Key Takeaways

  • The same key hormones are involved in male and female puberty and reproduction: GnRH, LH, and FSH
  • Ovulation & menstruation is about creating the opportunity for fertilization to occur if sperm is within close enough proximity
  • Men: if you want to conceive in the next 90 days, avoid elevating body temperature (e.g., hot tubs, hot baths, sauna, etc.) to optimize testes temperature and sperm health
  • Many miscarriages, trisomy abnormalities, failures at fertilization, and birth defects occur because egg and sperm chromosomes are not properly pulled apart into haploids
  • There is evidence that heat from laptops and electronics on the lap are negatively impacting sperm count
  • Frequency of intercourse for conception: abstain from intercourse 2-3 days before ovulation; then on the day prior to ovulation or the day of ovulation, have as much intercourse as you can/want
    • Successful fertilization largely depends on the quality of the egg 
  • Err on the side of conservative when trying to conceive and talk to OB/GYN at the onset of your desire to have children; the probability of conceiving naturally decreases throughout 30s due to the diminishing quality of eggs


Dr. Andrew Huberman, Ph.D. is a Professor of Neurobiology and Ophthalmology at Stanford University School of Medicine. His lab focuses on neural regeneration, neuroplasticity, and brain states such as stress, focus, fear, and optimal performance.

In part 1 of 2 part coverage of the Huberman Lab Podcast, Andrew Huberman comprehensively breaks down the biology and lifestyle factors of male & female fertility. He reviews the mechanisms of sperm and egg generation, optimizing the health of sperm and eggs, lifestyle factors that contribute to fertility, best practices for conceiving children, and a host of topics in between.

Host: Andrew Huberman (@hubermanlab)

Understanding The Components Of Fertility

  • Fertility and fertilization are about producing offspring that contains the genetic expression of both parents in equal ratios
  • Sperm and egg cells are part of the germline – meaning their genetic component (i.e., DNA) can’t be modified by behavior
  • Females do not make eggs beyond birth: eggs contain all chromosomes (23 pairs) of DNA and are present in females during embryonic development
  • Male chromosome is XY; Female chromosome is XX
  • Egg and sperm in close proximity leads to fertilization, bringing together 23 single strands of chromosomes from the male and 23 single strands of chromosomes from female
    • The purpose of the ovulatory and menstrual cycle is to eliminate half of the pairs in 23 chromosomes, allowing for the possibility of fertilization with sperm

Female Puberty

  • The onset of puberty is trending earlier every decade, across the world (for example, in the U.S. in 1900 the average age of female puberty was 14 and decreased to 11 by 1990(
  • Potential theories: increased body fat, accessibility to increased nutrition which signals maturation to brain and body
  • Melatonin and GABA suppress puberty
  • Puberty in females allows the ovulatory and menstrual cycles to start
  • The onset of puberty is happening earlier in females now than in the past, possibly because of an increase in body fat
  • Behavior & psychosocial interactions can also influence puberty

Female Reproductive Cycle: Ovulatory-Menstrual Cycle

  • The menstrual cycle does not just mean period – it’s referring to the entire cycle
  • Cycle length is between 21-35 days (the average cycle is 28 days); consistency is the main thing signaling health
  • Ovulatory-menstrual cycle is initiated in the brain by the release of GnRH (gonadotropin-releasing hormone)
    • GnRH signals to the anterior pituitary in the brain to release two main hormones: luteinizing hormone (LH) and follicle-stimulating hormone (FSH) which travel in the blood and change the genetic expression of cells
  • Follicular phase: first 14 days of the menstrual cycle where LH and FSH travel to the ovary and trigger maturation of some follicles
    • Egg is maturing and making its own hormones   
    • All but one single egg of maturing follicles die off
    • Chromosomes pairs are pulled apart and an egg containing chromosomes fuses with the wall of the ovary and is released into the fallopian tube, ready for fertilization if it takes place
    • Estrogen is released during this phase, triggering ovulation
  • Progesterone levels increase around the time of ovulation and drastically increase over the second half of the ovulatory cycle
  • Luteal phase: second half of menstrual cycle; discarded tissue produces a dramatic increase in progesterone
    • This phase can come with malaise for some women
  • Progesterone impacts the mucus lining of the uterus (where the egg would implant if fertilized)
  • If the egg is fertilized, pregnancy occurs; if the egg is not fertilized, period occurs
    • If menstruation occurs, inhibin and progesterone levels drop, and follicular phase stars again
  • In many women, there’s a dramatic increase in libido 4-5 days prior to menstruation because of an increase in LH, FSH, and androgen since the goal is to fertilize the egg

Sperm: What It Is, How It Travels, Health

  • Sperm are part of germline (like eggs), meaning our behaviors won’t change the genome of sperm
    • Lifestyle factors will modify the quality of sperm though
  • Job of sperm is to deliver genetic material from the father in the form of 23 chromosomes (haploid cells) and one sex chromosome (X or Y) in a way that increases the probability that the egg will be fertilized, progress healthily, and grow and maintain in healthy way
  • Sperm are swimming cells
  • Hormones involved in spermatogenesis (process of generating new sperm): GnRH, FSH, LH, and testes as target
    • Testes descend outside the body to ensure a cool enough environment for sperm to generate; If testes don’t descend on time, this requires medical attention
    • Keeping the testes cooler than the rest of the body is essential for sperm to live
    • Boxers or briefs? Doesn’t matter! Body will descend and retract testes as needed for cooling
    • Things that will increase scrotal temperature: big thighs (whether muscle or fat), seat warmers, hot tub, sauna, hot bath
  • Seminiferous tubules are the mesh-like structure of tubes in the testicle; immature sperm sits in the compartment along the edge of tubes, and move to the center as they mature before finally dropping in once mature
  • Seminal fluid is carrier fluid for sperm itself
    • Things that disrupt seminal fluid: drinking, smoking, and cannabis use
  • Vasectomy cuts vas deferens so no seminal fluid is released during orgasm/intercourse but all other aspects of erection, intercourse, and ejaculation are intact
    • Vasectomy is a reversible form of birth control for males
  • Morphology of sperm cell: sperm cells have a head (contains enzymes to deliver genetic contents), a body (responsible for cell motility and houses mitochondria), and a tail (generates how fast and how well sperm swims)


  • Spermatogenesis is the production and maturation of sperm
  • Unlike eggs, sperm are constantly being generated (it takes about 60 days to develop new sperm) – at any given moment, there are immature sperm in the testes (cannot swim), mature sperm in the testes, and dying or dead sperm
  • Similar to females, the hypothalamus up until the point of puberty is providing suppression of the release of GnRH, triggering the release of LH and FSH to the testes
  • Release of LH and FSH to testes and sets off the release of testosterone and production of sperm (spermatogenesis cycle)
  • There is a diminishment of sperm quality over time but it is constantly being created
  • LH secreted from the pituitary acts on the testes to produce testosterone
    • The concentration of testosterone in the testes is much higher than anywhere else in the body
    • Testosterone within testes acts on other cells in the testes to trigger spermatogenesis
  • Sperm motility is scored on a scale of 0-3 with the hope that more than 50% is motile
  • Target ejaculate volume: greater than 2 mL with a dense population but it will depend on the frequency of ejaculation and many other factors

Increasing Probability Of Fertilization

  • The goal is maximum number of high-quality sperm to increase the chances of fertilization
  • The egg is available for fertilization for approximately 24 hours
  • Frequency of intercourse for conception: abstain from intercourse 2-3 days before ovulation; then on the day prior to ovulation and the day of ovulation, have as much intercourse as you can
    • The goal is to optimize the concentration of sperm within each ejaculate and center around the day of ovulation
    • Yes, the number of high-quality sperm will be diminished the more you have sex
  • Age & quality of the egg (egg quality diminishes over time) is one of the most important factors in determining when and whether fertilization will occur
    • Estimating successful fertilization via intercourse with ejaculation day of ovulation and the day after (assuming sperm is healthy):
      • For women 30 and under, about 20% of the time will get pregnant the first month of attempting
      • General advice: women 30 and under should attempt to conceive over 6 months
      • For women 31-33, the probability of conceiving in the first month is about 18%
      • For women 34-37, the probability of conceiving in the first month is about 11%
      • General advice: women 34 and over should attempt to conceive over 9-12 months
      • For women 38-39, the probability of conceiving in the first month is about 5%
  • A key step for conception is for women to track ovulation, whether through body temperature, ovulation stick, app, or some combination of the above
  • Sperm will survive 3-5 days within the female reproductive system, post ejaculation – this allows for a little margin of error in ovulation tracking
  • Commercially available lubricants can be detrimental for conception because they change the environment and impact health and motility of sperm


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Notes By Maryann

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