Skip to content

Health & Pregnancy

Font Size

How to Chart Your Menstrual Cycle

Getting pregnant is all about timing. You want to make sure the conditions are right for egg and sperm to meet. Your menstrual cycle can give you clues about when your body is ready to start the process.

The first step is to learn the days when you’re most fertile. A woman with a 28-day menstrual cycle, for example, has about 6 days each month when she can conceive – the day one of her ovaries releases an egg, called ovulation, and the 5 days before. Timing sex within that window is key.

To figure it out, start charting your menstrual cycle and recording how long it lasts. Day 1 is the first day of your period. Since the length of your cycle can vary slightly from month to month, it’s best to keep track for a few months.

Then, subtract 18 days from the length of your shortest cycle: this is the first day you’re likely to be fertile. Next, subtract 11 days from the length of your longest cycle: this is the last day you’re likely to be fertile. Having sex between those two dates will give you the best shot at getting pregnant.

It’s also a good idea to pay attention to the signs that your body is ready to ovulate.

Basal Body Temperature

Your basal body temperature (BBT) is your temperature first thing in the morning. Just after you ovulate, it rises slightly -- sometimes by less than a degree -- and stays higher until your period starts. If you record your temperature every day, you can detect the subtle changes that mean one of your ovaries has released an egg.

How to take your BBT:

  • Use a basal body thermometer. They’re more sensitive than standard ones and will show temperature changes down to a fraction of a degree. You can get them at many pharmacies for less than $20.
  • Take your temperature at the same time each morning, always before you get out of bed. (Try keeping the thermometer on your nightstand.) Even getting up to go to the bathroom can affect your body temperature, as can smoking, drinking, or getting a bad night’s sleep.
  • Remember, your BBT won’t tell you exactly when you’ve ovulated, and it may take a couple of months before you start to see a pattern. You’re most likely to get pregnant 2 or 3 days before your ovary releases an egg, and then another 12 to 24 hours after that. When your temperature has spiked for 3 days, your chances of conceiving drop.

Pregnancy Week-By-Week Newsletter

Delivered right to your inbox, get pictures and facts on
what to expect each week of your pregnancy.

Today on WebMD

hand circling date on calendar
Track your most fertile days.
woman looking at ultrasound
Week-by-week pregnancy guide.
Pretty pregnant woman timing contaction pains
The signs to watch out for.
pregnant woman in hospital
Are there ways to do it naturally?
slideshow fetal development
pregnancy first trimester warning signs
What Causes Bipolar
Woman trying on dress in store
pregnant woman
Close up on eyes of baby breastfeeding
healthtool pregnancy calendar
eddleman prepare your body pregnancy