November 13, 2023 • 3hr 23min
Dr. Natalie Crawford: Female Hormone Health, Fertility & Vitality
Huberman Lab
Key Takeaways
- Females are born with all the eggs they will ever have - about 6-7 million at 20 weeks gestation, reduced to 1-2 million at birth. Eggs are constantly lost from the "vault" throughout life, not just during ovulation.
- Puberty in females typically begins with breast development around age 10-11, followed by first menstruation (menarche) about 2 years later. The age of puberty onset does not impact how long fertility will last.
- The menstrual cycle has two main phases - the follicular phase before ovulation and the luteal phase after. The luteal phase is fairly fixed at 12-14 days, while the follicular phase can vary in length.
- Hormonal birth control does not diminish egg count or future fertility. It prevents ovulation but does not change the natural loss of eggs from the ovaries.
- Egg freezing and IVF do not reduce future fertility or egg count. They access eggs that would have been lost that month anyway.
- AMH testing and antral follicle count ultrasounds can assess ovarian reserve, but are not routinely recommended for screening. However, this information can be very valuable for family planning.
- Egg quality declines significantly with age, especially after 37. By age 40, only about 20-25% of eggs are chromosomally normal.
- Lifestyle factors like nutrition, sleep, stress management and avoiding toxins can help optimize fertility and egg quality. Supplements like CoQ10, omega-3s, and vitamin D may also be beneficial.
- IVF success rates vary widely based on age and whether genetic testing of embryos is done. With tested embryos, live birth rates can be up to 65% per transfer.
- Early menopause is associated with increased health risks. Hormone replacement therapy started early in menopause can improve quality of life and longevity.
Introduction
In this episode, Dr. Andrew Huberman interviews Dr. Natalie Crawford, a reproductive endocrinologist and fertility specialist. They discuss female hormones, fertility, and reproductive health across the lifespan - from fetal development through menopause. Dr. Crawford provides detailed explanations of the menstrual cycle, ovarian reserve, egg freezing, IVF, and other key topics in reproductive medicine. She also offers evidence-based advice on optimizing fertility through lifestyle factors and addresses common misconceptions about birth control and fertility treatments.
Topics Discussed
Female Puberty and Development (4:59)
- Females are born with all their eggs - about 6-7 million at 20 weeks gestation, reduced to 1-2 million at birth
- Eggs are constantly lost from the "vault" throughout life, not just during ovulation
- Puberty typically begins with breast development around age 10-11, followed by pubic/underarm hair growth
- First menstruation (menarche) occurs about 2 years after breast development starts
- The age of puberty onset does not impact how long fertility will last
The Menstrual Cycle (26:04)
- Two main phases - follicular phase before ovulation and luteal phase after
- Follicular phase: FSH stimulates follicle growth and estrogen production
- Luteal phase: Corpus luteum produces progesterone
- Luteal phase is fairly fixed at 12-14 days, follicular phase can vary in length
- Normal cycle length ranges from about 24-35 days
Birth Control and Fertility (38:08)
- Hormonal birth control does not diminish egg count or future fertility
- It prevents ovulation but does not change the natural loss of eggs from the ovaries
- Can temporarily suppress AMH levels, which may appear low while on birth control
- Copper IUDs work by creating an inflammatory environment toxic to sperm
- Hormonal IUDs thin the uterine lining and may suppress ovulation in some women
Egg Freezing and IVF (1:35:40)
- Do not reduce future fertility or egg count - they access eggs that would have been lost that month anyway
- Involves ovarian stimulation with FSH/LH to grow multiple follicles
- Eggs are retrieved vaginally under sedation, then frozen or fertilized
- ICSI (intracytoplasmic sperm injection) is commonly used to fertilize eggs
- Success rates decline with age due to decreasing egg quality
Assessing Ovarian Reserve (1:24:50)
- AMH blood test measures hormone produced by small follicles
- Antral follicle count ultrasound counts visible follicles
- Not routinely recommended for screening but can provide valuable information
- AMH and follicle count decline with age, especially after 37
Optimizing Fertility (2:20:36)
- Sleep is critical for cellular repair and lowering inflammation
- Diet high in fruits, vegetables, whole grains, and healthy fats
- Moderate exercise and stress management
- Avoid toxins, smoking, excessive alcohol
- Supplements like prenatal vitamins, CoQ10, omega-3s, vitamin D may be beneficial
IVF Success Rates (3:11:45)
- Vary widely based on age and whether genetic testing of embryos is done
- With tested embryos, live birth rates can be up to 65% per transfer
- Without testing, success rates are lower, especially for older women
- Multiple cycles may be needed, especially for women over 35
Menopause (3:15:10)
- Average age is 51-52 but can occur earlier or later
- Early menopause associated with increased health risks
- Symptoms include irregular periods, hot flashes, mood changes, vaginal dryness
- Hormone replacement therapy started early can improve quality of life and longevity
Conclusion
This episode provided a comprehensive overview of female reproductive health and fertility. Dr. Crawford emphasized that fertility is a reflection of overall health and that lifestyle factors can have a significant impact. She dispelled common myths, like the idea that egg freezing or birth control diminish future fertility. The discussion highlighted how reproductive medicine has advanced, with technologies like egg freezing and genetic testing of embryos offering new options for family planning. However, age remains the most important factor affecting fertility, with egg quality declining sharply after age 37. Dr. Crawford encouraged women to be proactive about understanding their fertility and considering their options, rather than waiting until problems arise. Overall, this episode offers valuable information for anyone interested in optimizing their reproductive health or considering fertility treatments.
