Difference Between PMS and Pregnancy Symptoms

By Dr. Victor Chang 7 Min Read

Premenstrual syndrome (PMS) and early pregnancy symptoms can feel remarkably similar, often making it challenging for women to distinguish between the two. Both conditions involve hormonal changes that affect the body, leading to various physical and emotional symptoms.

While some signs overlap, key differences exist between PMS and pregnancy symptoms that can help in recognizing which one you might be experiencing. In this article, we will delve into these similarities and differences, helping you better understand your body and what it may be signaling.

The Hormonal Connection

Both PMS and pregnancy are driven by hormonal changes, which is why they share several symptoms. PMS occurs as part of the menstrual cycle, typically a few days to two weeks before menstruation begins, and is influenced by fluctuations in estrogen and progesterone. Pregnancy symptoms, on the other hand, result from hormonal changes, such as an increase in human chorionic gonadotropin (hCG) and progesterone, which sustain the developing pregnancy.

Because both situations involve a significant shift in hormone levels, it’s unsurprising that the body responds with similar symptoms in both cases. However, some distinct signs and patterns differentiate the two, which can provide clues as to whether you’re dealing with PMS or pregnancy.

Common Symptoms of PMS and Early Pregnancy

Breast Changes

  • PMS: Tender or swollen breasts are a classic symptom of PMS, often occurring 1-2 weeks before menstruation. The discomfort usually subsides once the period begins or shortly after.
  • Pregnancy: In early pregnancy, breasts may feel swollen, tender, or sore. However, this discomfort often lasts longer, extending well past the missed period, and may be accompanied by darkening of the areolas.

Fatigue

  • PMS: Feeling tired or sluggish is a common PMS symptom, usually occurring in the days leading up to menstruation due to a drop in hormone levels.
  • Pregnancy: Fatigue is also an early sign of pregnancy, often more intense and persistent. This is due to increased levels of progesterone and the body adjusting to new physical demands.

Mood Swings

  • PMS: Mood swings, irritability, and feeling emotionally sensitive are often seen in PMS. These emotional changes tend to be cyclical and resolve after menstruation begins.
  • Pregnancy: Mood swings are also common in early pregnancy due to surging hormone levels, but they may be more pronounced and longer-lasting.

Cramping

  • PMS: Mild to moderate cramps (also called dysmenorrhea) are typical in PMS and are usually felt in the lower abdomen or back just before or during the period.
  • Pregnancy: Cramping can also occur in early pregnancy, but it is often lighter and more focused on implantation (called implantation cramps), which occur when the fertilized egg attaches to the uterine lining. Women can experience mild cramps in the lower abdomen, which are common during early pregnancy as the uterus stretches and grows. 

Key Differences Between PMS and Pregnancy Symptoms

While PMS and early pregnancy symptoms overlap in many areas, distinct differences can help distinguish between the two. Let’s look at some key points of distinction.

Nausea

  • PMS: Nausea is not a typical PMS symptom, although some women may experience digestive upset or bloating.
  • Pregnancy: Nausea, often referred to as “morning sickness,” is one of the hallmark signs of pregnancy. It can begin as early as two weeks after conception and may persist for several weeks or months.

Menstruation

  • PMS: The most definitive difference is that PMS leads to menstruation or a period. Once your period starts, most PMS symptoms, like breast tenderness and mood swings, will resolve.
  • Pregnancy: Pregnancy, on the other hand, results in a missed period. If your period does not arrive as expected, it could be an early sign of pregnancy.

Implantation Bleeding

  • PMS: PMS does not cause any kind of bleeding before menstruation.
  • Pregnancy: Some women may experience light spotting, called implantation bleeding, about 6-12 days after conception. This watery period blood sign of pregnancy. This is much lighter than a period and lasts only a day or two.

Food Cravings and Aversions

  • PMS: Many women experience cravings for specific foods or increased appetite during PMS.
  • Pregnancy: Pregnancy can cause cravings, but it’s also common to have food aversions. Certain smells or tastes may suddenly become intolerable, even if they were previously enjoyed.

Basal Body Temperature

  • PMS: Basal body temperature (BBT) generally rises slightly after ovulation and returns to normal before menstruation.
  • Pregnancy: If pregnant, BBT remains elevated after ovulation due to the sustained production of progesterone.

When to Take a Pregnancy Test

If you suspect that you might be pregnant, the most definitive way to know is to take a pregnancy test. It’s best to wait until you have missed your period for the most accurate result, as hCG levels will be high enough to detect by then. Testing too early, like before 15-20 days after the unprotected sex occurred, may result in a false negative.

The Bottom Line

The symptoms of PMS and early pregnancy can overlap significantly, making it difficult to differentiate between the two without the help of a pregnancy test. However, subtle differences, such as nausea, the duration of certain symptoms, and the absence of menstruation, can offer important clues. Understanding these signs can help you better recognize what your body is experiencing and take the next steps, whether preparing for your period or confirming a pregnancy.

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