Ovulation comes immediately after the follicular phase. Around day 14 of a typical 28-day cycle, a surge of luteinizing hormone (LH) triggers the ovary to release a mature egg. This brief ovulatory event then gives way to the luteal phase, the final stretch of the menstrual cycle before your period begins.
Ovulation: The Transition Point
During the follicular phase, several egg-containing follicles begin developing inside the ovary, and one becomes dominant. When estrogen from that dominant follicle reaches a high enough level, it triggers a sudden spike in LH. Within about 36 hours of that LH surge, the ovary releases the egg. This is ovulation, and it typically lasts only 12 to 24 hours.
Your body gives off a few signals around this time. Cervical mucus becomes clear, slippery, and stretchy, often compared to raw egg whites. This change is driven by rising estrogen and makes it easier for sperm to travel. After ovulation, the mucus thickens again and becomes white or pasty. Your basal body temperature also rises slightly, typically less than half a degree Fahrenheit, and stays elevated through the rest of the cycle.
The Luteal Phase Begins
Once the egg leaves the follicle, the empty sac doesn’t just disappear. It transforms into a temporary structure called the corpus luteum, a yellow mass of cells that forms where the follicle once was. The corpus luteum takes on a new job: producing progesterone, along with some estrogen. Progesterone is the dominant hormone of this phase, and its primary role is preparing the uterine lining to support a potential pregnancy.
The luteal phase lasts 12 to 14 days on average, though anywhere from 10 to 17 days falls within the normal range. Unlike the follicular phase, which can vary quite a bit in length from person to person (14 to 21 days is typical), the luteal phase tends to be more consistent. This is why longer or shorter cycles are usually the result of a longer or shorter follicular phase, not changes in the luteal phase.
What Happens If Pregnancy Doesn’t Occur
If the egg is not fertilized, the corpus luteum has a built-in expiration date. Without a pregnancy signal, it gradually breaks down. As it degrades, progesterone and estrogen levels drop sharply. That hormone withdrawal destabilizes the thickened uterine lining, and the lining sheds. This is your period, and it marks both the end of the luteal phase and the start of a new follicular phase.
What Happens If Pregnancy Does Occur
When a fertilized egg implants in the uterine wall, the early pregnancy produces a hormone called hCG (human chorionic gonadotropin). This hormone signals the corpus luteum to keep producing progesterone instead of breaking down. The corpus luteum sustains hormone production for roughly the first 10 weeks of pregnancy, until the placenta develops enough to take over.
How the Full Cycle Fits Together
In a standard 28-day cycle, the timeline looks roughly like this: the follicular phase occupies days 1 through 13 (starting with your period), ovulation happens around day 14, and the luteal phase runs from day 15 through day 28. But menstrual cycles commonly range from 28 to 35 days, and the follicular phase accounts for most of that variation. Someone with a 35-day cycle likely has a longer follicular phase, not a longer luteal phase.
If you’re tracking your cycle, the shift from the follicular to the luteal phase shows up in a few measurable ways. Ovulation predictor kits detect the LH surge in urine and give a positive result about 36 hours before the egg is released. Cervical mucus shifts from its peak egg-white consistency back to thicker and drier. And basal body temperature, when charted daily, shows a small but sustained rise after ovulation that stays elevated until your next period starts. Together, these signs confirm that the follicular phase has ended and your body has moved into the progesterone-dominant luteal phase.