Short Follicular Phase: Is It Hard to Get Pregnant?

When you’re trying to conceive, tracking your basal body temperature (BBT) can tell you a lot about your fertility over the course of your cycle. But if your chart shows the follicular phase of your cycle is on the short side, you might wonder if this will make it harder to get pregnant. Let’s go through the basics of what follicular phase length means for you.

What happens in the follicular phase, anyway?

follicular phase luteal menstrual cycle

The follicular phase refers to the first part of your menstrual cycle: right after your period, but before your body release this month’s fertile egg at ovulation. It’s called the “follicular phase” because it’s during this time that the ovarian follicle containing the egg cell grows and matures.

During this phase of your cycle, your estrogen levels rise, and your body temperature stays on the low side. After ovulation, when the ovarian follicle bursts open to release the egg, you produce more of the hormone progesterone. Progesterone makes your temperature rise a little bit. This changeover in body temperature is what accounts for the biphasic pattern you see on a BBT chart.

Is it hard to get pregnant with a short follicular phase?

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It may be hard to get pregnant with a short follicular phase. The average follicular phase lasts 13 to 15 days. However, this phase is more variable than the second half of the menstrual cycle.

When you see differences in overall cycle length between women, or even in the same woman from month to month, it’s usually down to differences in the length of the follicular phase. So how short is too short?

It’s thought that a follicular phase that lasts less than 13 days is short and could mean trouble for fertility. Even if you did release an egg in the short follicular phase, it may not be fully mature, and could have trouble implanting into the uterine lining to begin a pregnancy after fertilization.

What causes short follicular phases?

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If your follicular phase becomes shorter, it could be a sign of an underlying hormone imbalance. If your reproductive hormones are out of whack, it could trigger the release of an underdeveloped egg cell.

Short follicular phases can also be associated with the phenomenon of age-related ovarian decline. Since you’re born with a limited supply of egg cells, they progressively run out and die away as you approach menopause.

As the body releases more follicle-stimulating hormone (FSH) to compensate, it can trigger earlier ovulation and result in a short follicular phase. This is usually seen in middle age, but also in early menopause. Unfortunately, this can make it more difficult to conceive naturally.

What should I do for a short follicular phase?

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Unless you’re measuring your BBT, a short follicular phase may just appear as a shorter-than-usual menstrual cycle. Temporary blips in cycle length may happen as a result of everything from factors such as illness or emotional stress.

Keeping a close record of your BBT for at least 3 cycles in a row will give you an impression of whether this is a sign of an underlying hormone imbalance. If your BBT chart registers a follicular phase of 12 days or less for a few cycles in a row, speak to your gynecologist.

A blood test can check the levels of hormones such as FSH in your system and see if there’s an underlying condition. Your doctor may recommend a course of ovary-stimulating fertility drugs to nudge your menstrual cycle back into a healthier pattern.

Don’t ignore a short follicular phase

basal body temperature chart

By measuring your BBT, you’ll have an extra tool for identifying changes in the follicular phase that could interfere with your fertility. If you think yours is on the short side for a few cycles in a row, don’t hesitate to see your OB-GYN: there are effective treatments available to help get your cycle back on track.