Changes in the fetus and mother in the 31st week of pregnancy

By (embryologist) and (embryologist).
Last Update: 02/15/2024

In the 31st week of pregnancy, the woman is in the eighth month of gestation, that is, in the third trimester. Therefore, due to the advanced stage of gestation and the size that the belly has already reached, it is likely that the woman will notice more and more discomfort.

It is common that, in week 31, it is increasingly difficult for the pregnant woman to move around and, at times, it will be difficult for her to fall asleep. In addition, the woman may notice changes in her breasts, which are already preparing to breastfeed the baby.

The baby in the 31st week of pregnancy

The baby's measurements at 31 weeks of pregnancy are about 40-41 cm in length and about 1600-1700 grams in weight. The baby is accumulating fat under the skin, which will serve to regulate its temperature when it is born.

In addition, the baby's skin (previously more wrinkled) begins to soften, presenting an appearance more similar to what it will look like after delivery.

On the other hand, their eyelids open and their pupils may constrict or dilate, which will occur in response to light stimuli if there is a light source close to the belly.

By the 31st week of pregnancy, the baby's kidneys are capable of producing approximately half a liter of urine daily. This becomes part of the amniotic fluid, thus involving the baby in its renewal.

Finally, it is possible that the baby is already in the cephalic position at 31 weeks gestation, that is, with the head oriented towards the maternal pelvis. Although it can still turn around, it will become less and less common as the space in the uterus becomes smaller and smaller.

Maternal symptoms in the 31st week of pregnancy

In the 31st week of pregnancy, a woman may be concerned because she notices certain contractions and may be unsure if they are labor contractions. Most commonly these are Braxton Hicks contractions.

These contractions make the belly hard and can be uncomfortable, but are painless. In addition, they differ from labor contractions because they are irregular and do not increase in intensity or frequency.

On the other hand, if the woman feels increasingly frequent and intense contractions, she should go to the doctor urgently, as she could be in premature labor.

On the other hand, when a woman is in the 31st week of pregnancy, it is common to notice other symptoms and discomforts such as the following:

  • Back pain.
  • Heartburn
  • Difficulty sleeping and insomnia.
  • Increased urge to urinate
  • Swelling of legs and hands, favored by changes in blood circulation. In addition, varicose veins may also appear.
  • Carpal tunnel syndrome, due to swelling of the hands, which causes the woman's hands to feel numb.
  • Vulvar swelling and even vulvar varicose veins.
  • Hemorrhoids.
  • Colostrum secretion, in preparation for lactation.

In addition, if the baby is breech positioned, it is common for the woman to feel some pressure in the upper belly (in the rib area) from the baby's head.

Medical control in the 31st week of pregnancy

If the pregnancy is not risky and is developing normally, the 31st week of pregnancy may not coincide with any hospital visits for medical tests.

However, a third trimester ultrasound will soon be performed on the pregnant woman. In general, this ultrasound is performed between 32 and 36 weeks of gestation and is used to evaluate the growth and position of the baby, the condition and location of the placenta and the volume of amniotic fluid.

Recommendations in week 31

It is important for the pregnant woman to follow a healthy, balanced and varied diet throughout her pregnancy, in order to provide all the necessary nutrients. It will also be essential to include fiber in the diet and to maintain proper hydration to avoid constipation. As an added benefit, drinking adequate amounts of water will also help prevent UTIs.

However, to reduce reflux and heartburn, it will be better for the pregnant woman to eat small but frequent meals.

Another tip that pregnant women can take into account is the use of creams or oils to avoid itching due to skin stretching and the appearance of stretch marks. On the other hand, the use of absorbent nursing pads can also help to avoid staining clothes with colostrum secretion.

Finally, it will be beneficial to engage in physical activity adapted to this stage of pregnancy, as well as to try to rest when possible.

FAQs from users

Is bleeding in the 31st week of pregnancy normal?

By Silvia Azaña Gutiérrez B.Sc., M.Sc. (embryologist).

Any bleeding in pregnancy should be consulted with the gynecologist, especially if the bleeding is intense or occurs along with other symptoms such as pain.

In addition, bleeding in the third trimester of pregnancy can have different causes, so it is best to see a specialist as soon as possible so that he/she can evaluate what is causing it.

Does the baby move a lot in the 31st week of pregnancy?

By Silvia Azaña Gutiérrez B.Sc., M.Sc. (embryologist).

In the 31st week of pregnancy the baby continues to move, but due to the lack of space inside the uterus (which is becoming more evident) the woman may notice fewer movements, but these are more intense.

What is happening if my belly gets hard in week 31 of pregnancy?

By Silvia Azaña Gutiérrez B.Sc., M.Sc. (embryologist).

The sensation of a hard belly at 31 weeks gestation may be caused by Braxton Hicks contractions. These are contractions that may be uncomfortable, but not painful, and occur irregularly in preparation for labor.

On the other hand, if the woman notices regular contractions that are becoming more frequent and intense, she should see a specialist quickly, as they may be labor contractions.

However, if the pregnant woman has any doubts or concerns, it is always best to consult her gynecologist.

Suggested for you

If you are 31 weeks pregnant and are interested in reading about what happens in the next week of gestation, we recommend you visit this article: Week 32 of pregnancy.

On the other hand, if you want to read more about prenatal pregnancy control, you can click on the following link: Prenatal pregnancy control.

We make a great effort to provide you with the highest quality information.

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FAQs from users: 'Is bleeding in the 31st week of pregnancy normal?', 'Does the baby move a lot in the 31st week of pregnancy?' and 'What is happening if my belly gets hard in week 31 of pregnancy?'.

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Authors and contributors

 Cristina Mestre Ferrer
Cristina Mestre Ferrer
B.Sc., M.Sc.
Bachelor's Degree in Biological Sciences, Genetics & Human Reproduction from the University of Valencia (UV). Master's Degree in Biotechnology of Human Assisted Reproduction from the UV and the Valencian Infertility Institute (IVI). Embryologist at IVI Barcelona. More information about Cristina Mestre Ferrer
 Silvia Azaña Gutiérrez
Silvia Azaña Gutiérrez
B.Sc., M.Sc.
Graduate in Health Biology from the University of Alcalá and specialized in Clinical Genetics from the same university. Master in Assisted Reproduction by the University of Valencia in collaboration with IVI clinics. More information about Silvia Azaña Gutiérrez
License: 3435-CV

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