Maybe you’re trying to get pregnant, or maybe you’re trying to avoid it. In both cases, the ability to identify when in your cycle you are ovulating is crucial. Your body gives distinct signs every cycle to tell you when you are possibly fertile, most fertile and infertile. Understanding and tracking these signs can be used to help you determine your fertile window and maximize the chances of getting pregnant, they can be used as a birth control method, and they can be used to identify any potential issues with your fertility such as PCOS and recurrent miscarriages.
Menstrual Cycle Basics
The menstrual cycle is composed of two distinct phases - the follicular phase and the luteal phase. In the follicular phase (also referred to as the estrogenic phase), estrogen levels increase, the egg gets primed for ovulation and the endometrial lining of the uterus grows. The increase in estrogen in this phase causes the cervix to produce and release fluid that helps sperm to survive and move efficiently to the egg. The follicular phase can vary considerably from woman to woman and can be impacted by factors such as stress, travel and illness.
Ovulation marks the end of the follicular phase and the start of the luteal phase (also known as the progesterogenic phase). Progesterone, the hormone that rises in the luteal phase of the cycle, is in charge of keeping the uterus primed and ready for implantation if pregnancy occurs. If pregnancy does not occur, progesterone falls and that’s when a woman gets her period, marking the end of the cycle. The luteal phase is much more consistent than the follicular phase. It is between 12-16 days long and tends to be the same from one cycle to the next. The increase in progesterone in this phase causes an increase in a woman’s waking body temperature.
Fertility Signs
There are three key signs your body gives you every cycle that tell you when you are ovulating. They include:
1. Basal Body Temperature (BBT)
A fancy way to say the temperature of your body when you wake up, the basal body temperature will tell you when you’ve ovulated. After an egg is released and progesterone levels rise, the body warms and a distinct rise in your temperature can be detected. A rise is temperature is considered 0.5-1.0 Fahrenheit, 0.2-0.4 degrees Celcius, or higher. For women trying to get pregnant, the BBT tells you that you have already ovulated.
2. Cervical Fluid
Cervical fluid is produced under the influence of estrogen in the first phase of the menstrual cycle. The cervix has small fluid producing glands that estrogen ‘turns on’. Cervical fluid can be seen as soon as your period ends, or there may be a gap between the end of your period and the start of cervical fluid. Cervical fluid typically starts out as a creamy or sticky consistency, getting wetter as ovulation comes closer. It is the wet cervical fluid, and specifically the “egg white”, stretchy cervical fluid that is most conducive to conception.
3. Cervical Position
The position of the cervix within the vagina changes every cycle. When not fertile, the cervix is low and closed. When fertile, the cervix moves high up in the vagina and opens up to maximize chances of getting pregnant. The position of your cervix can be checked manually.
The above three signs can be used together to help determine your most fertile window.
Ps. If you are interested in learning more about natural birth control, such as tracking your cycle through physiological signs, I highly recommend you read “Taking Charge of Your Fertility” by Toni Weschler.