Early pregnancy symptoms before a missed period vary among individuals. They are often similar to the symptoms of other conditions and changes, including premenstrual syndrome (PMS).
The hormone human chorionic gonadotropin (hCG) causes many of the first symptoms of pregnancy. However, in the days following implantation before a woman misses her period, levels of this hormone are low. As a result, although some women report early pregnancy symptoms at this time, others experience none at all.
Read on to learn about the earliest symptoms of pregnancy before a missed period and other causes of a missed period.
Pregnancy begins with implantation, which happens when the fertilized egg embeds in the lining of the uterus. Implantation stimulates the production of hCG, a hormone that the body produces in progressively larger amounts in early pregnancy.
The hCG then stimulates the production of another hormone, progesterone. Together, the two hormones cause early pregnancy symptoms.
Implantation usually occurs a few days before a missed period. Therefore, hCG levels are still low by the time a woman expects her period. Due to these low levels, some women notice no symptoms at all or only experience very subtle symptoms, which they may attribute to something else.
Among the most common early pregnancy symptoms are nausea and vomiting. Many pregnant women report that nausea and vomiting are worse when they are hungry or have low blood sugar. Therefore, women who notice symptoms of nausea between meals or when they wake up hungry may be pregnant.
Some other common early pregnancy symptoms include:
- fatigue that ranges from mild to intense
- tender, sore, or swollen breasts
- darker nipples
- more frequent urination, which is due to hormonal causes rather than to pressure on the bladder
- food or smell aversions
- food cravings
- changes in mood or emotion, such as increased anxiety, weepiness, or shifts in energy level
- spotting or light bleeding — known as implantation bleeding — before an expected period or at any time during the first trimester
The intensity of these symptoms often increases during the first trimester, as hCG levels rise. Toward the end of the first trimester, many women notice that symptoms improve.
In early pregnancy, hormonal shifts, not the growing fetus, cause pregnancy symptoms. As pregnancy continues, other symptoms may appear.
Pregnancy can cause a wide range of symptoms between conception and delivery, including:
In very early pregnancy, symptoms are usually mild. Due to this, it is easy to mistake pregnancy symptoms for normal aches and pains.
Hormonal shifts that happen as a woman’s period approaches may cause symptoms that also appear in pregnancy — for example, breast tenderness and swelling. Some women with PMS can experience these symptoms ahead of every period.
In some cases, a woman may still experience the symptoms of early pregnancy despite not being pregnant. Possible reasons for this include:
- Chemical pregnancy: A chemical pregnancy involves a very early pregnancy loss. Doctors diagnose it when a home pregnancy test or blood test confirms a pregnancy that an ultrasound does not then show. In some cases, women will not realize that a chemical pregnancy has occurred.
- Illness: A cold, the flu, or another infection can cause fatigue, muscle aches, nausea, vomiting, and other symptoms.
- Increased bodily awareness: Women hoping to get pregnant may become more vigilant about noticing any changes in their body. The normal aches, pains, and twinges of everyday life may become more apparent. Some women may attribute any symptoms that they experience to pregnancy.
- Anxiety about trying to get pregnant: Both trying to get pregnant and trying to avoid pregnancy can increase anxiety. Some women notice intense mood swings before their periods. They may attribute these emotions to pregnancy hormones when they are instead a reaction to anxiety about pregnancy.
A missed period can occur for many reasons, including:
- Period delay: If a woman ovulates a few days later than usual, this may delay her period by a few days.
- Hormone disorders: Numerous conditions can cause hormonal imbalances that delay ovulation, or even suppress it, resulting in a missed period.
- An early pregnancy loss: A chemical pregnancy, or early pregnancy loss, can sometimes cause a positive test that a negative test then follows. In some cases, the “late period” that occurs is an early pregnancy loss.
- Malnourishment: Women who are very underweight or eating too few calories may not ovulate, which can cause their periods to disappear. Doctors refer to this as amenorrhea.
- Perimenopause: A woman entering menopause may ovulate less frequently, causing fewer periods. This stage is known as perimenopause.
A positive pregnancy test is only possible if:
- A woman’s body is producing hCG: A positive pregnancy test can only happen after implantation, and not just after the fertilization of an egg. Therefore, most women can only get a positive result a few days before their expected period.
- The test is sensitive enough to detect hCG levels: Most tests cannot register hCG levels until this hormone has risen for several days following implantation.
False negatives are common, especially if people perform the test too early. If a woman has noticed signs and symptoms of pregnancy and her period still does not come, she should wait a few days and then test again.
It is important to see a doctor for:
- a period that is very late, even if a pregnancy test is negative — this is especially important if the woman is trying to get pregnant or is worried that she may have a hormone issue
- symptoms of pregnancy that do not go away following a negative test, as they may signal another problem, such as an infection
- a positive pregnancy test
- bleeding following a positive pregnancy test
- persistent or severe abdominal pain
Some early symptoms of pregnancy before a missed period include nausea, breast tenderness, and fatigue. However, these are also common signs of other problems, such as hormonal changes.
If women have pregnancy symptoms, they should take a pregnancy test.
If the result is negative and their period does not come, they should speak to a doctor for an assessment and diagnosis. For women who receive a positive result with no period shortly after, a doctor can confirm the pregnancy.
Taking a pregnancy test is the best way to determine whether a woman is pregnant. As early pregnancy symptoms are so similar to signs of other issues, they are not a reliable basis for diagnosing pregnancy.