Main causes of abdominal pain during pregnancy


In this article, we will analyze the main causes of abdominal pain during pregnancy, as well as the warning signs that all pregnant women need to be aware of.

The following conditions will be addressed in this text:

  • “Normal” abdominal pain during pregnancy.
  • Ectopic pregnancy.
  • Miscarriage.
  • Braxton Hicks contractions.
  • Round ligament pain.
  • Labor.
  • Placental abruption.
  • Preeclampsia
  • Urinary infection during pregnancy.


During pregnancy, due to the countless physiological and anatomical changes within the body, it is usual for women to experience some episodes of abdominal and pelvic pain, with variable intensity.

Although most causes of abdominal pain during pregnancy are harmless and expected, some of them may be a sign of a more serious problem. Apart from complications inherent to pregnancy, such as ectopic pregnancy, miscarriage or problems in the uterus or placenta, the pregnant women can also have any abdominal diseases common to the general population, such as appendicitis, cholecystitis, pancreatitis, urinary tract infection, gastroenteritis, etc.

As such, if you are pregnant, it is important to educate yourself about the most common causes of abdominal pain during pregnancy, so that you are able to recognize the symptoms that may indicate potentially serious problems.

Abdominal pain during pregnancy caused by pregnancy itself

Harmless episodes of abdominal or pelvic pain usually start in the first few months and can last until the end of pregnancy. The “normal” abdominal pain of pregnancy is typically intermittent, but in some cases it can appear very frequently throughout the 9 months of gestation.

The causes of abdominal pain, as well as its characteristics, change during the course of pregnancy. Some of the common causes of “normal” pregnancy discomfort include: hormonal variations, changes in the abdominal and pelvic anatomy, uterine growth, uterine contractions, fetal movement, and pelvic ligaments abnormalities.

There are also pregnancy pains that are not considered normal, that is, discomforts caused by complications of the pregnancy itself. These types of pains, which may indicate a more serious problem, need to be recognized early, so that the pregnant woman can seek obstetric care immediately, minimizing the risks of complications.

From now on, we will explain the main causes of abdominal pain during pregnancy, according to the gestational trimester.

Common causes of abdominal pain during the first trimester of pregnancy

1. Normal pregnancy discomforts during the first trimester

In the first months of pregnancy, abdominal pain is usually caused by hormonal changes that interfere with the normal functioning of the bowels. Excessive gas, bloating, and constipation are some of the problems that result in abdominal cramps as early as the first trimester (read: 20 EARLY SYMPTOMS OF PREGNANCY).

In general, these cramps are mild and transient and do not have any other associated symptoms. Therefore, any abdominal pain that is severe and persistent, or accompanied by other symptoms, such as vaginal bleeding, purulent vaginal discharge, fever, intense or bloody diarrhea, hypotension, prostration, or vomiting*, must be evaluated by the obstetrician.

* Nausea and vomiting are common during the first trimester of pregnancy, however they are not usually associated with abdominal pain, fever, or diarrhea.

2. Abdominal pain related to complications during the first trimester of pregnancy

During the first trimester of gestation there are two main causes of abdominal pain due to pregnancy complications: ectopic pregnancy and miscarriage.


If the pregnancy develops outside the uterus, for example, within the Fallopian tubes, it is called an ectopic pregnancy.

Obviously, aside from the uterus, no other structure in our body is prepared to develop an embryo. Therefore, serious complications can arise when the fetus begins to grow outside the uterus. A common example is a ruptured Fallopian tube, which is a life-threatening medical emergency.

Symptoms of an ectopic pregnancy usually appear around the 6th week of pregnancy. The most common are:

  • Moderate to severe pain, usually in the lower abdomen (the pain is more intense in the side where the ectopic embryo is located).
  • Increased abdominal wall rigidity.
  • Vaginal bleeding.
  • Painful bowel movement.
  • Lump in groin area (in cases of ectopic pregnancy in one of the fallopian tubes).
  • Nausea and vomiting.

The diagnosis is usually made through ultrasonography, which can demonstrate that the embryo is not located inside the uterus.


A miscarriage (or spontaneous abortion) is any natural interruption of pregnancy occurring before 20 weeks of gestation. Pregnancies that come to an end after the 20th week, but before due time are referred to as preterm delivery.

Miscarriage is one of the main causes of abdominal pain during the first trimester of gestation. Most spontaneous abortions occur within the first 13 weeks of pregnancy.

Signs and symptoms of a miscarriage include:

  • Moderate to intense abdominal cramps.
  • Pelvic or back pain.
  • Mild to moderate vaginal bleeding.
  • White-pink mucus.
  • Expulsion of tissue with clot like appearance from the vagina.
  • Uterine contractions that appear every 5 to 20 minutes. These cramps may resemble those of menstruation.

Gynecological examination and ultrasound are usually required to confirm a miscarriage.

Common causes of abdominal pain during the second trimester of pregnancy

1. Normal pregnancy pain during the second trimester

By the 12th week of pregnancy, the uterus has already grown enough to become an intra-abdominal organ (previously, it was located solely in the pelvic region). Therefore, in addition to all the causes of “natural” abdominal pain during the first trimester, a pregnant woman now begins to experience pain and discomfort caused by the compression of abdominal organs by the uterus, along with the progressive increases in weight that the pelvis must support.

Among the harmless causes of abdominal pain beginning on the second trimester of pregnancy, two stand out: Braxton Hicks contractions and round ligament pain.


The so-called Braxton Hicks contractions are non-expulsive uterine contractions, which usually begin from the 2nd trimester of pregnancy (in some women they appear at the end of the first trimester) and serve as “training contractions” for the uterus. These contractions are harmless and cause more annoyance than pain.

Typical Braxton Hicks contractions are painless, short-lived, with irregular intervals and low frequency, and do not increase the risk of premature delivery.

In general, simply shifting position and resting are enough to make them disappear. Dehydration can trigger this type of contraction, which is why most doctors suggest drinking more water to reduce its frequency.


The round ligament is responsible for connecting the uterus to the pelvic region. As the uterus grows and becomes heavier, the round ligament becomes more and more overloaded.

Stretching of the round ligament usually occurs during the second trimester, and increases as the pregnancy progresses. It usually provokes a stabbing pain in the pelvis or lower abdomen every time the woman changes position. Getting out of bed, coughing, getting up from a chair and getting out of a car are some situations that can trigger this kind of pain.

Round ligament pain may also become constant after a very active day, in which the pregnant woman has exerted herself more than she should have.

2. Abdominal pain related to complications during the second trimester of pregnancy

As the pregnancy progresses, the number of possible gestational complications also increases, especially after the 20th week. Let’s discuss briefly some of these complications, which usually occur accompanied by abdominal pain. The conditions described below are also valid for the third trimester of gestation.


Any delivery that occurs after the 37th week of pregnancy is considered normal or “term”. On the other hand, we call premature (or preterm) labor when it occurs before the 37th week of gestation. The more premature the delivery, the less time the baby has had for intrauterine development, thus increasing the risk of complications for the newborn.

As with miscarriage, premature labor also manifests with abdominal pain. The most common symptoms are:

  • Frequent and rhythmic uterine contractions that intensify as time goes by.
  • Mild vaginal bleeding.
  • Water breaking.
  • Pelvic or lower abdominal pressure
  • Constant low back pain.

A pregnant woman should contact her obstetrician immediately upon the smallest sign of preterm birth. The doctor will perform a gynecological exam to check if the uterus is indeed trying to expel the fetus.


Placental abruption occurs when the placenta completely or partially separates from the wall of the uterus before childbirth. This is a serious complication because the detachment prevents the placenta from receiving blood from the uterus circulation, putting the life of the fetus at risk.

Placental abruption is more common during the third trimester of pregnancy, but it can occur anytime after 20 weeks of gestation.

The most common symptoms of placental abruption are:

  • Vaginal bleeding, which may be heavy or light.
  • Intense abdominal and low back pain.
  • Uterine contractions.
  • Hypotension (in cases of heavy bleeding).

Placental abruption is also a medical emergency, and labor induction is usually the best way to treat the problem.


Preeclampsia is a syndrome characterized by the onset of hypertension and proteinuria (abnormally large amounts of protein in the urine) after 20 weeks of pregnancy. In severe cases, the liver may also be demaged.

The most common symptoms include abdominal pain, swelling of the face and hands, headache, blurred vision, nausea and vomiting. When the patient with preeclampsia presents with a seizure, the condition is called eclampsia.


Other less common gestational complications that may cause abdominal pain, occuring from the second trimester, include:

  • Uterine rupture.
  • Amniotic fluid infection.
  • Uterine incarceration.
  • Cholestasis of pregnancy.
  • Spontaneous hemoperitoneum.

Causes of abdominal pain not related to pregnancy

Just like any individual, a pregnant woman may also develop abdominal conditions that are not specific to pregnancy, such as appendicitis, cholecystitis, gastroenteritis or kidney stones. The diagnosis of these problems is usually more difficult during pregnancy due to the several changes that the abdominal region has undergone. Even the location of the pain may be atypical.

Among the dozens of abdominal complications that may occur during gestation, but are not directly related to pregnancy, one stands out: urinary tract infection.

Urinary infection during pregnancy

Cystitis (bladder infection) is a common problem during pregnancy and may occur at any time during gestation. The most common symptoms include:

  • Painful urination.
  • Frequent urination.
  • Urinary incontinence.
  • Urge to urinate, even when the bladder is empty.
  • Blood in urine (hematuria).

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