What is a luteal phase defect?
A luteal phase defect is a term for a luteal phase that is too short, usually under 10 days, or that produces too little progesterone to support the uterine lining. It has been linked to difficulty conceiving and early miscarriage, but experts still debate how to diagnose it and whether it is a cause of infertility on its own.
What it looks like in a cycle
A typical luteal phase lasts 12 to 14 days. With a luteal phase defect, the time from ovulation to your period may be 8 or 9 days, or there may be spotting for several days before the period proper. Some people only find out when they start temping or using ovulation tests.
Possible causes
- High stress, intense exercise or low energy intake
- Thyroid problems or raised prolactin
- PCOS or obesity
- Perimenopause, as ovulation becomes less consistent
- Breastfeeding and the months after birth
Why doctors debate it
The American Society for Reproductive Medicine has said there is no reliable test for it, because short luteal phases and low progesterone readings also happen in people who conceive normally. So doctors usually look for an underlying cause instead of treating the label. See short luteal phase for the practical side.
If your luteal phase is consistently under 10 days and you're trying to conceive, or you have repeated early losses, talk to a doctor. Bring a few months of cycle and ovulation dates.
Frequently asked questions
How do I know my luteal phase length?
Count from the day after ovulation to the day before your period. Confirming ovulation with basal body temperature or tests makes it more accurate.
Can a short luteal phase fix itself?
Often, yes. One short phase is common. It may lengthen once stress, sleep, nutrition or a thyroid problem are addressed.
Sources
This page is for information only and isn鈥檛 medical advice. If something worries you, please talk to a doctor.
Keep reading
What is a short luteal phase, and does it matter?A short luteal phase is 10 days or fewer from ovulation to period. What causes it, what the research says about fertility, and when to see a doctor.
Luteal phase: definition and meaningThe luteal phase is the part of your cycle from ovulation to your next period, usually 12 to 14 days. Hormones, mood, PMS and why it matters.
Progesterone: definition and meaningProgesterone is the hormone made after ovulation that prepares the uterus for pregnancy. Its role in the luteal phase, PMS, mood, sleep and temperature.
Luteal phase calculator: how long is my luteal phase?Free luteal phase calculator: enter your ovulation day and next period to see your luteal phase length and whether it sits in the typical 11 to 17 day range.
Infertility: definition and meaningInfertility means not getting pregnant after 12 months of regular unprotected sex, or 6 months if you're 35 or older. Causes, tests and next steps.