The Truth About PMS Symptoms vs. Pregnancy Symptoms

Anyone trying to conceive knows about the nerve-wracking "two-week wait," the time between ovulation and when you can reliably find out if you're pregnant. Can't stop wondering whether you'll get your period or a positive pregnancy test? Read on to learn about the similarities and differences between PMS symptoms and pregnancy symptoms, and what to do while you wait.

Tracking Your Symptoms After Ovulation

It can be tempting to analyze every perceivable symptom after ovulation to try to figure out if you're pregnant or not. But when you're in the two-week wait, patience is truly key. That's because the earliest symptoms of pregnancy will not become apparent until well after ovulation.

The truth is, depending on the timing of sperm entering the vagina and when the egg is released during ovulation, it can be near impossible to know the exact day of fertilization. The egg only lives for 24 hours, but sperm can live for up to five days in the female reproductive tract, so unless you know exactly when you ovulated, there's a six-day fertile window.

Then, once the egg is fertilized, it has to travel to the uterus and implant in the uterine lining, another several-day process. At the very, very earliest, if everything is perfectly timed and goes swimmingly (no pun intended), some people get a positive pregnancy test result as early as six days post-ovulation, but that is pretty uncommon. Instead, it's best to wait until your expected period to look for early signs of pregnancy.

Most modern pregnancy tests are capable of detecting pregnancy about two weeks after ovulation. But how early you can get a positive test result depends on how sensitive the pregnancy test is and how much hCG your body is producing. The level of hCG can range widely among pregnancies; however, an at-home pregnancy test can reliably detect hCG levels as low as 20 to 50 milli-international units, which is around the level of hCG at four weeks post-conception.

PMS Symptoms vs. Pregnancy Symptoms

It can feel like a cruel reality that PMS symptoms and the early signs of pregnancy are nearly identical. The reason? Hormones. One of the main culprits during the two-week wait is progesterone. Your body produces more progesterone in the weeks after ovulation, whether you're pregnant or not. Progesterone is one of the hormones responsible for many PMS symptoms, like bloating, breast tenderness, and mood swings.

If you're not pregnant, your body will stop releasing progesterone about 10 days after ovulation. Then, as the hormone levels wear off, your symptoms subside, the uterine lining sloughs off, and you get your period.

If you are pregnant, you'll continue producing progesterone (and experiencing PMS-like symptoms). "The difference between PMS and early pregnancy is very subtle," says Helen Kim, MD, associate professor of obstetrics and gynecology and director of the In Vitro Fertilization Program at the University of Chicago.

And while it is true that the only sure-fire way to know if you're pregnant or not is to take a pregnancy test, one hopeful—but subtle—difference between PMS symptoms vs. pregnancy symptoms is that PMS is not likely to make you feel nauseated or vomit, a common pregnancy symptom.

Pregnancy Bleeding and Cramping vs. Your Period

According to the American Academy of Obstetrics and Gynecology (ACOG), first-trimester bleeding occurs in 15% to 25% of pregnancies. Sometimes, the bleeding is caused by implantation, which happens when the fertilized egg attaches to the lining of your uterus. Implantation bleeding usually starts around the time you expect your period or a few days sooner and can easily be mistaken for the start of menstruation. It might also be accompanied by mild cramping that feels like pulling or tingling.

There are a few distinctions between implantation bleeding and menstruation, though: "Implantation bleeding tends to be lighter and shorter in duration than a period," says Dr. Kim. Unlike menses, spotting associated with implantation will stay light and won't develop into a full flow. But if you don't experience implantation bleeding, don't fret: You can still be pregnant and have a healthy pregnancy without it.

What to Do During the 'Two-Week Wait'

The two-week wait between ovulation and your expected period can feel excruciatingly long when you're desperate to know if you're pregnant. Instead of fretting and wondering, use this time to prepare your body for a possible pregnancy. Whether or not you're pregnant, the habits you establish will help prepare your body for if and when you are.

Treat your body like it's pregnant

Experts recommend acting like you're pregnant until you know for sure—especially when you're actively trying to conceive. You don't have to go overboard with restrictions, but you should treat your body as if it's pregnant because you could be, Dr. Kim says. Avoid alcohol, limit yourself to one to two cups of coffee per day, skip fish high in mercury, and avoid raw or undercooked seafood, meat, poultry, and eggs.

Take a prenatal vitamin

Once you start trying to conceive, ACOG recommends you start taking a prenatal vitamin that contains at least 400 micrograms of folic acid (the synthetic form of folate that's commonly found in vitamin supplements), to help prevent neural tube defects (NTDs). If you have certain risk factors, like a previous baby with an NTD, you may need to take more folate or folic acid.

Adequate levels of folate are especially important in early pregnancy because a baby's neural tube (which becomes the baby's brain and spinal cord) develops during the first four weeks of pregnancy. Don't worry if you haven't taken them yet; it's never too late to start.

Stay active

You should also be mindful of your physical fitness, no matter your two-week wait symptoms. "If you normally engage in moderate-intensity physical activity, keep it up," says Dr. Kim. That's because exercise is a great way to relieve stress, and stress affects your overall health and your fertility.

Still, Dr. Kim warns that this isn't the best time to adopt a new or intense training program, which can stress your nervous system. You'll also want to avoid activities that significantly raise your core body temperature, such as hot yoga or heated spinning, because they could negatively affect implantation.

So, choose moderate-intensity exercises. For example, walking is a generally safe and accessible activity for all fitness levels. But, to be sure, talk to a health care provider to discuss options that are safest for you.

When To See a Health Care Provider

If you consistently get your period less than 14 days after you ovulate, see a health care provider as it could be a red flag that something is affecting your ability to become pregnant. It could be as minor as miscalculating ovulation, or it could be a condition like polycystic ovary syndrome (PCOS). Other situations that may warrant a trip to the doctor can include the following:

• You have negative pregnancy tests but still no period.
• You're over 35 and you've been trying to conceive for 6 months with no positive pregnancy test.