We all know that there is a specific time of month when a woman is most likely able to conceive. For women trying to conceive--and even those who are not--they track not only their menstrual cycles, but something called a basal body temperature. Basal body temperatures help determine when a woman is ovulating and most likely to get pregnant, but what temperatures should you look for, and how exactly does this work? We're about to break it down.
Simply put, a basal body temperature is the temperature your body is when fully at rest--meaning the best time to take this temperature is right when you wake up. When ovulating, a woman's body creates LH, or luteinizing hormone, which is responsible for the release of an egg into the fallopian tube. When your body has a high amount of LH, meaning you are ovulating, a woman's body temperature dips and then slightly raises, accounting for about a .2 to .4 degrees Fahrenheit variation in basal temperature, according to a study in The Journal of Fertility and Sterility. Therefore, tracking your basal temperature can tell you exactly when your LH levels are up, and your eggs are free to be fertilized.
A woman's body and fertility works, quite literally, like clockwork. Not only are menstrual cycles vital in our reproductive ability, but there are a variety of other cycles all occurring to help you get pregnant. A change in basal temperature signals a shift in hormones known as the "circamensal rhythm," which is the basal temperature version of a menstrual cycle. Within the circamensal rhythm, there is the acrophase: the period of time where your basal temperature is the hottest. Acrophase occurs late in the luteal cycle (typically the day after you ovulate), which is the explanation for the dip in temperature prior to heating up.
Mayo Clinic says it's important to take your basal temperature as the same time every day, and right when you wake up in the morning. It's vital to take your temperature at the same location (orally, rectally, or vaginally) when charting to ensure consistency when recording them. Be extremely careful with glass and mercury thermometers, especially if taking basal temperatures vaginally or rectally, and sanitize instruments after every use.
There are apps and tools to help chart basal temperatures available to make your tracking easier. Of course, it's important to consider that basal temperatures may vary due to environmental factors and sickness as well.However, basal temperatures are by no means a gold standard for determining fertility, but can be used by women committed to using this as their form of family planning or birth control.
There is no one-size-fits-all for measuring ovulation, but there are simple, affordable over-the-counter ovulation predictor kits (OPKs) that can ease any other issues that may arise in basal charting. Once you find what's right for you, your family planning can be made easy. If you still struggle to get pregnant despite frequent sexual activity, contact a fertility expert to help identify any underlying issues with conceiving.