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The First Days of the Cycle: Preparing the Ground for Life

NNova editorial team · 5 min read

From the first day of your period, your body starts rebuilding the uterine lining and growing follicles in the ovaries. These changes help prepare the uterus so an embryo can implant if pregnancy happens later in the cycle.

A Fresh Start

The first day of your period marks the start of your menstrual cycle. During this time, hormone levels begin to shift, signaling the body to start the renewal process.

The uterus sheds the endometrium (the lining that was prepared for a possible embryo in the previous cycle). Over the next days, the body begins building a new lining for a possible pregnancy.

Behind the Scenes

  • Follicle growth: small fluid-filled sacs in the ovaries, called follicles, begin to develop. Several follicles grow, and usually one becomes dominant and releases an egg during ovulation.
  • Endometrial repair: under the influence of estrogen, the uterine lining begins to thicken.
  • Hormonal tuning: the body gradually prepares for ovulation later in the cycle.
Cycle length varies from person to person, and some month-to-month changes in timing are common.

When to Talk to Your Doctor

Many providers recommend contacting them about certain changes that may need a medical opinion.

Contact your healthcare provider right away if you have extremely heavy bleeding, such as soaking through a pad or more every hour for several hours, or severe abdominal pain. Seek emergency care if you also feel faint, dizzy, or short of breath.

Read more about week 2.

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General information only; it does not replace advice from your doctor or midwife.