What happens in the 39th week of pregnancy? Expulsion of the mucus plug

By (embryologist) and (psychologist).
Last Update: 04/12/2022

In just 7 days the last week of pregnancy will arrive. Most pregnant women feel heavy and have discomfort that prevents them from doing routine tasks such as getting dressed or putting on their shoes.

The gynecologist will do an examination of your abdomen to see exactly where your baby is positioned. Another routine test is to examine the cervix to see how it is, if it is thinner at the time it is checked or if there is dilatation.

At 39 weeks gestation, the cervix is preparing for delivery. At this time it is possible to feel the famous Braxton Hicks contractions quite strong.

At any time, labor can occur, so it is important to recognize the symptoms, contractions, and rupture of the amniotic sac, which is popularly known as water breaking. If this happens call the doctor, you are in labor.

What does the fetus look like at 39 weeks?

When the pregnancy is about to end, the baby is practically unchanged. At 39 weeks gestation, the fetuses weigh about 3.2 kg and are approximately 46 cm long. These data may vary from one pregnancy to another, as some babies may be slightly longer or shorter in length and weight.

As a consequence of this size, it is normal for the mother not to feel much movement of the baby since there is practically no space left for it. Nevertheless, the kicks will continue and will be felt.

On the other hand, a detachment of the white fat or vernix caseosa usually occurs in the 39th week of pregnancy. This fat is formed in mid-pregnancy and its function is to protect the fetus from cold and humidity.

Changes in the mother

The tenth and last month of pregnancy is almost over, so there are few changes for the mother-to-be. The uterus of pregnant women changes throughout gestation, going from 500 grams to approximately 1 kg.

The cervix is already prepared for delivery and the bladder is under pressure due to the size of the future baby. In addition, the woman will feel more and more nervous because the long-awaited day is approaching.

Maternal symptoms at 39 weeks

When the woman reaches 39 weeks of pregnancy, she is heavy and has difficulty moving. In addition, pregnant women are often on the lookout for any signs that may indicate they are going into labor.

Some of the most common discomforts and symptoms in the 39th week of pregnancy are:

  • Increased number of contractions, similar to cramps.
  • Loss of mucous plug.
  • Diarrhea
  • Nausea.
  • Back pain.
  • Fatigue.
  • Increased desire to sleep.

In the event of early labor, the woman's water will break and she will expel amniotic fluid. There is no exact way to break water, as it will depend on the position of the fetus. If this occurs, you should go to the hospital immediately.

Recommendations for week 39

The baby is about to be born and, as mentioned above, the woman may feel heaviness in her legs or in her body in general. Therefore, one of the tips for the 39th week of gestation is to try to sleep and rest. In addition, it is advisable to walk as much as possible, unless the doctor says otherwise.

Contractions may be increasing during this stage. When you have increasingly stronger contractions and the frequency decreases, you may be in labor. At this point, you should see a doctor.

Finally, nerves are likely to be on edge. Try to stay relaxed and keep practicing your childbirth preparation exercises.

FAQs from users

Is the mucus plug expelled in the 39th week of pregnancy?

By Marta Barranquero Gómez B.Sc., M.Sc. (embryologist).

It is possible. The mucous plug is a secretion formed largely by water, although it also has glycoproteins. Its function is to seal the cervix.

This plug usually forms around week 7 of gestation and remains until the end of pregnancy, around week 36-38. When the mucus plug is expelled, the woman may or may not go into labor immediately.

It is also possible that the woman may feel that the plug is being expelled little by little, i.e. progressively. When the mucus plug is gone, labor may occur within hours or even a few weeks.

Can you induce labor naturally?

By Victoria Moliner BSc, MSc (embryologist).

Inducing labor is totally unadvisable unless medically indicated. Even if you are more than 40 weeks pregnant and your baby is still in your belly, you have to let your pregnancy continue unless otherwise determined by your doctor. However, in post-term or prolonged pregnancies, labor is typically induced to prevent problems in the baby and/or the mother.

Is it normal for the baby to move little in the 39th week of pregnancy?

By Marta Barranquero Gómez B.Sc., M.Sc. (embryologist).

Yes, the baby weighs about 3200 grams and is about 46 cm long. Therefore, the free space left in the uterus is limited and, therefore, it will not move as much as it did at the beginning when it was smaller.

If you want to know what is going to happen in the next and last week of pregnancy, we recommend you to visit the following article: What is the 40th week of pregnancy like?

If what you want is to know how childbirth is going to be so that you can be prepared when the time comes, you can visit this link: How is childbirth? Preparation, types, and possible complications.

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

🙏 Please share this article if you liked it. 💜💜 You help us continue!


Kirsti Krohn Garnæs, Trude Elvebakk, Øyvind Salvesen, Signe Nilssen Stafne, Siv Mørkved, Kjell Åsmund Salvesen, Trine Moholdt. Dietary Intake in Early Pregnancy and Glycemia in Late Pregnancy among Women with Obesity. Nutrients. 2021 Dec 27;14(1):105. doi: 10.3390/nu14010105 (see)

Lærke Kristine Kyhl, Ellen Kristina Leth Løkkegaard. Appendicitis in late pregnancy. Ugeskr Laeger. 2021 Apr 26;183(17):V10200789.

Lia Keiko Sousa Shimamura, Denise Leite Maia Monteiro, Célia Regina da Silva, Flávio Eduardo Frony Morgado, Flávio Monteiro de Souza, Nádia Cristina Pinheiro Rodrigues. Late pregnancy: impact on prematurity and newborn's weight. Rev Assoc Med Bras (1992). 2021 Nov;67(11):1550-1557. doi: 10.1590/1806-9282.20210454 (see)

Rachel A Tinius, Maire M Blankenship, Karen E Furgal, W Todd Cade, Cathryn Duchette, Kevin J Pearson, Jill M Maples. Metabolic flexibility during late pregnancy is associated with neonatal adiposity. Appl Physiol Nutr Metab. 2021 Apr;46(4):404-407 (see)

FAQs from users: 'Is the mucus plug expelled in the 39th week of pregnancy?', 'Can you induce labor naturally?' and 'Is it normal for the baby to move little in the 39th week of pregnancy?'.

Read more


 Marta Barranquero Gómez
Marta Barranquero Gómez
B.Sc., M.Sc.
Graduated in Biochemistry and Biomedical Sciences by the University of Valencia (UV) and specialized in Assisted Reproduction by the University of Alcalá de Henares (UAH) in collaboration with Ginefiv and in Clinical Genetics by the University of Alcalá de Henares (UAH). More information about Marta Barranquero Gómez
License: 3316-CV
Adapted into english by:
 Cristina  Algarra Goosman
Cristina Algarra Goosman
B.Sc., M.Sc.
Graduated in Psychology by the University of Valencia (UV) and specialized in Clinical Psychology by the European University Center and specific training in Infertility: Legal, Medical and Psychosocial Aspects by University of Valencia (UV) and ADEIT.
More information about Cristina Algarra Goosman
Member number: CV16874

Find the latest news on assisted reproduction in our channels.