Main causes of contractions in the third trimester of pregnancy 2026

Although you can have contractions before the time of birth of the baby originally approaches, the truth is that they will not really begin, and in earnest, until the day of delivery arrives. It is true that you may experience an occasional, annoying and uncomfortable tension in the stomach, which means that the uterus is preparing for the big finale, but it should not be confused with the typical contractions of labor.

As we have already mentioned in previous moments, there are different types of contractions, so those that arise during labor are not the only ones that appear. We find a good example with Braxton Hicks contractions, although there are also others that we should mention.

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Early contractions usually feel like a tightening and tightening of the stomach, becoming a clear sign that the body is preparing both for labor and for the birth itself. That is, the uterus is exercising for the grand finale, and for the arrival of the baby.

The causes? The stretching of the ligaments located around the uterus. Although they are not the only ones. They can also arise from gas, constipation or dehydration, so originally they would have nothing to do with contractions.

There are also Braxton Hicks contractions, which arise from the second trimester and are also often called “false” contractions. Generally, they tend to last between 30 seconds and 2 minutes, and occur randomly (although, admittedly, they can also appear after exercise or sexual relations). Again, they are a sign that the uterus is preparing for childbirth.

But there are also other related causes that can influence the appearance of contractions. Below, we discover some of the most common ones.

1. Excessive effort

Some women feel tired and fatigued throughout pregnancy, and especially during the third trimester, when the size and weight of the baby influence this. However, others feel the need not to slow down. However, overloading the body could cause the uterus to begin to undergo “false” contractions (that is, the typical - and well-known - Braxton Hicks contractions).

The truth is that they are characterized by being quite practical contractions, since they help the body prepare for childbirth. Luckily, they often tend to disappear when the pregnant woman relaxes or puts her feet up. In addition, they are characterized by being sporadic, arising randomly, and lasting between 30 seconds and 2 minutes.

They usually appear after 20 weeks of pregnancy. Unless other symptoms - such as bleeding or spotting - arise, it is not necessary to call the doctor.

2. Premature labor

It is considered that we are in premature labor when it occurs before the 36th week of pregnancy has ended. And they are characterized by a pattern of tension or twisting of the uterine wall, which tends not to disappear.

If before that week you have many contractions, for several hours in a row, and they do not disappear, it is necessary to go to the doctor so that the pregnant woman can be properly evaluated.

Early labor can lead to premature birth, which is often related to low birth weight, fetal breathing problems, vision problems, and other complications.

3. Have sex

It is false to believe that sexual relations can negatively influence labor. But it is known that having sexual intercourse can be related to Braxton Hicks contractions.

Experts believe this could be because protaglandins naturally present in semen, and orgasms, cause the uterus to contract. However, it is common that these false contractions tend to disappear shortly after they start.

Again, if they become more intense or longer, or follow a predictable pattern, you need to call or see your doctor.

4. Complications of pregnancy

If intense, painful contractions and vaginal bleeding develop, it is essential to see a doctor immediately, especially if the feeling of tightness and pain lasts more than 2 minutes.

The reason? Contractions that do not tend to go away are usually an obvious sign of problems, so if they do not rest or take a break, they could indicate a dangerous complication, such as a uterine rupture.

5. You are in labor

Obviously, the most common cause of contractions in late pregnancy is labor. Although it is true that they can start irregularly, when the probable day of delivery has been reached, it is common for them to soon begin to have a much more regular rhythm.

In this sense, and if it is a real labor, the contractions, little by little, will tend to get closer, and will be longer, more intense and stronger.