When are the Best Days to Get Pregnant?
You know the old joke about the rhythm method for contraception. “What do you call people who use the rhythm method? Parents.” All jokes aside, methods for monitoring a woman’s fertile period have been in use for many years, with varying degrees of success in preventing or causing pregnancy. They all hinge on trying to determine when you are ovulating and having sex or artificial insemination within a few days before or after, if you want to get pregnant, or abstaining, if you don’t. The “fertile window” is defined as the 6 day interval ending on the day of ovulation, but the highest chances of pregnancy occur within 3 days of the day of ovulation.
Common methods include tracking your menstrual cycle, measuring basal body temperature, and measuring the presence of luteinizing hormone (LH.) Even just being more aware of your body and how you feel may let you know when you are ovulating. And there are new online monitors and tools to help with these techniques. Here’s a brief recap of each method.
Tracking Your Menstrual Cycles
Keeping a record of your menstrual cycles is the basis of the rhythm method. Ovulation usually occurs in the middle of your menstrual cycle. The first day of your cycle is the day bleeding starts, and the cycle ends when bleeding starts again, the first day of the next cycle. The average length of a menstrual cycle is 28 days, which makes around day 14 when ovulation happens. However, normal cycles can range from 21 to 35 days, which can make predicting ovulation more difficult.
By keeping a menstrual calendar you can figure out what is normal for you. If your periods are irregular this method may not be accurate for you. There are several online menstrual calendars. Here is one from the March of Dimes.
Basal Body Temperature Charting
You need a special thermometer to measure your basal body temperature (BBT)—a regular thermometer will not work for this. Your BBT is the first reading you take when you wake up in the morning, before you get out of bed or do anything else at all. Basically, your BBT is lowest just before ovulation and then rises about half a degree the day of ovulation. Tracking your BBT will tell you when ovulation has already occurred. If you track it for a few months you may be able to tell the pattern of when you are ovulating, and thus will know the days in your cycle when you are more likely to get pregnant.
However (again), other things can affect your basal body temperature in addition to the hormones released before and after ovulation. If you have a cold or an infection the pattern may be disrupted.
Know Your Body, Part I
The Germans have a word for it—“mittelschmerz,” or “middle pain.” Many women feel a slight, brief pain or a series of cramps in their lower abdomen when they ovulate, usually on the side where the ovary is that is releasing an egg. Not everyone notices this, for normally the pain is quite mild. Be aware and you may be able to actually feel ovulation!
Know Your Body, Part II
Cervical mucus is different from the slippery fluid your vagina produces when you are sexually aroused. It is a little stickier and kind of like egg white in consistency. Its purpose is to prepare a safe landing zone for the sperm at ovulation and help move the sperm along to fertilize the egg. When ovulation is getting ready to occur, your body produces more cervical mucus and it becomes thinner and clearer. Within a few days after ovulation has happened, the mucus either dries up or becomes much thicker.
Changes in cervical mucus have been proven in studies to be good indicators of ovulation. So if you keep an eye on the changes “down there,” especially in combination with another method, you may be able to pinpoint your most fertile days.
Ovulation Predictor Kits
These popular over-the-counter kits measure the level of luteinizing hormone (LH), which is the last of the hormones to peak when ovulation occurs. These tests pinpoint your day of ovulation 12 to 36 hours in advance and are easy to do at home. These kits are most useful for couples having infrequent intercourse in order to be certain that sperm are present at the time of ovulation.
Some newer tests measure changes in the estrogen level in your saliva (your spit) or in the salts in your sweat, which change at different times of the month depending on what is going on with your cycle. This change in your sweat, called the chloride ion surge, happens earlier than the estrogen surge or the increase in LH and can tip you off to ovulation as much as four days in advance. This kit requires figuring out your baseline level in advance, so it takes some pre-planning.