Updated by the Progyny Clinical Team — June 2025.
Fertility and your menstrual cycle
The time when you’re most likely to get pregnant is around ovulation. This is when your ovaries release an egg. The timing can be different for everyone, depending on how long and regular your cycle is. If your cycle is 28 days long, ovulation usually happens between day 13 and day 15. Day 1 is the first day of full menstrual bleeding — not just light spotting.
Best time to have sex to conceive
The best time to have sex to achieve a pregnancy is a few days before ovulation occurs. This is because an egg survives for about 12 to 24 hours after ovulation. However, sperm can stay alive in the body for three to five days. That means you’re fertile for about a six-day window. Couples should have sex at least every two days starting five days before ovulation until the day after ovulation.
Detecting ovulation
To make the most out of each session of sexual intercourse, you need to know when you are ovulating. There are several methods to detect the start of ovulation:
Changes in cervical mucus
Cervical mucus can be an indicator of ovulation. Before ovulation, cervical mucus is dry and sticky. As ovulation comes closer, it may take on a creamier consistency. Right before ovulation, cervical mucus tends to take on the consistency of a raw egg white and may become more slippery.
For some, charting cervical mucus can help identify cycle patterns. Others may find it difficult to reliably detect changes from month to month.
Charting basal body temperature (BBT)
Charting your BBT can help you detect patterns of ovulation.
When taking your temperature every morning before you get up, you may detect a 0.4-degree Fahrenheit increase after ovulation. Most thermometers on the market can be used, as they generally measure temperature to the tenth degree.
This method is most helpful in planning for upcoming cycles. That’s because you’re most fertile before ovulation and the increase in temperature is after it.
Ovulation predictor kits
These at-home tests allow you to predict when you will ovulate. The test works by measuring urinary luteinizing hormone (LH), a hormone that sharply rises mid-cycle to signal the ovary to release an egg. Ovulation should occur in the 12 to 48 hours after you detect a rise in LH. The surge lasts up to 36 hours, meaning that the test is only positive for one to two days.
These kits can be misleading for some people, particularly those with irregular cycles or polycystic ovarian syndrome.
Physical signs of ovulation
Ovulation signs can be different for everyone, but they may include light spotting, cramps, sore breasts, and bloating.
If you have questions, Progyny is here for you. Please contact your Progyny Care Advocate for support.
Disclaimer: The information provided by Progyny is for educational purposes only and is not medical advice. Always consult a qualified healthcare provider for medical guidance.
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This five minute video features Carol Lesser, NP from Boston IVF.