Many of us know that ovulation is the phase during the menstrual cycle when you can get pregnant, but what exactly happens in your body during ovulation? For those who haven’t spent time trying to conceive a baby, you’re probably a lot more familiar with the period part of your cycle than with ovulation. If the last time you got an in-depth description of ovulation was high school sex ed, here’s the low-down on what’s going on during this phase.
The Nitty Gritty
There are 4 phases of your menstrual cycle: menstrual, follicular, ovulation, and luteal. Ovulation is the shortest phase, lasting only a day or two out of a cycle that can be between 22 and 35 days. The monthly process of ovulation is governed by hormones which relay chemical signals between your brain and your ovaries that let your body know when to release an egg each month.
During the follicular phase, the phase preceding ovulation, the brain releases follicle-stimulating hormone (FSH) which causes multiple follicles in your ovaries to mature. However, toward the end of the follicular phase, in the days right before ovulation, only one follicle fully matures an egg to release into the fallopian tube. As this one follicle matures, it begins to produce estradiol, a form of estrogen. The estradiol in this mature follicle cues the brain to increase production of luteinizing hormone. Luteinizing hormone (LH) in turn cues the follicle to grow bigger in size until it eventually ruptures, releasing the egg into the fallopian tube. The other follicles begin to disintegrate. As soon as the egg has been released into the fallopian tube, ovulation has begun.
The act of ovulation transforms the follicle that released an egg into what is called the corpus luteum which is latin for “yellow body.” The corpus luteum produces the hormone progesterone. Progesterone prepares the body for pregnancy if the egg is fertilized. An egg only survives for 12-24 hours and must be fertilized by sperm in this time if a pregnancy is to be achieved. Typically fertilization happens in the fallopian tube. Then the egg continues its journey down the tube and into the uterus. The journey to the uterus takes about 30 hours. Once in the uterus, a fertilized egg may implant in the uterine wall. This takes 5 or 6 days. If implantation occurs, the implanted embryo will begin to produce human chorionic gonadotropin (hCG) and that's what a pregnancy test is going to detect. If the egg is not fertilized, it dissolves after about 24 hours.
Ovulation and Behavior
You may have heard claims that when you are ovulating, you are most attractive to others, your skin glows more, or potential mates can somehow pick up on your heightened fertility. There is still much more research that needs to be done before we can definitively say that ovulation changes how you look or behave. However, there are some preliminary studies that suggest that ovulation might impact attraction, flirtation, and dating/mating behaviors.
For example, one study of 237 women showed that women tend to show a heightened preference for social presence and competitiveness in males on fertile days versus non-fertile days. Another study with 51 participants shows that women reported being more attracted to someone who was not their primary partner on their fertile days.These participants also noted that their primary partners seemed more attentive and focused on them during their fertile days.
Unlike your period that announces itself with blood, it’s hard to know for sure if you are ovulating. Even ovulation kits and tests work by telling you when you have had a surge of luteinizing hormones in the days before ovulation, they don’t tell you exactly when you are ovulating, but measuring your progesterone levels after you ovulated can confirm whether or not ovulation took place. One sign of ovulation that you might observe is a change in your vaginal discharge (cervical mucus). During ovulation, vaginal discharge is often described to be like egg whites: clear and slippery to the touch. You may notice having more discharge than at other times in your cycle. Some people also experience symptoms similar to those that they experience during their period such as breast tenderness. That pain on one side of your lower abdomen that shows up in the middle of your cycle (14ish days before you bleed)? It's called mittelschmerz, and it's not totally clear why it happens — it could be the egg enlarging right before it's released from the ovary, or maybe it's blood emerging from the ruptured follicle. Not everyone who ovulates experiences mittelschmerz, and not everyone who does gets it every month. Some people have bleeding and nausea along with this pain. You should talk to your doctor if your mittelschmerz is particularly bad.
Ovulation and Fertility
Unlike an egg which is only fertile for 12-14 hours, sperm can survive inside the uterus for up to six days after unprotected sex. During ovulation, the mucus covering the cervix is thinner and easier for sperm to make their way through to reach the uterus. The first sperm make their way up the vagina, through the cervix and uterus, and into the fallopian tubes within minutes of ejaculation (minutes!). However, sperm will continue to make their way toward the fallopian tubes over the next six days. For this reason, about a week of each cycle is considered to be a fertile week. If you have sexual intercourse anytime in the week before your egg releases, you have a much higher likelihood of getting pregnant.
Some people also monitor their ovulation to avoid getting pregnant by tracking their basal body temperature, cervical mucus, and/or the calendar. These methods of preventing pregnancy are called FAMs or Fertility Awareness Methods. One of the pros of FAMs is that you become more familiar with your cycle, and therefore may be able to spot any oddities that could indicate a medical condition, such as polycystic ovary syndrome (PCOS) or the beginning of the menopausal transition, when periods become more irregular. FAMs also don’t require any type of hormonal instruments (like an IUD) to control fertility. However, potential cons are that properly executing FAMs requires sustained attention and monitoring and, in practice, FAMs are about 76-88% effective at preventing pregnancy. This means that 24-12 women out of 100 will get pregnant each month when using the FAM method of contraception.
Whether you are thinking about conception or not, understanding ovulation gives you more information about your body and connects you to your cycle and other aspects of your reproductive health. If you're curious to learn more, check out some information on ovulation trackers or on the Fertility Awareness Method. You can also learn more about your fertility with one of Modern Fertility home testing kits, which will give you important facts about your hormones so, if and when you want to start prepping for kids for real, you'll have some vital info with which to move forward.