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Pregnancy Week to Month Converter

Reviewed by MD Katiuska Ríos Calderón

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Converting Weeks to Months of Pregnancy

Converting Months to Weeks of Pregnancy


  • Weeks of pregnancy = Months of pregnancy
  • Months of pregnancy = Weeks of pregnancy
  • With weeks you are in month of pregnancy.
  • In the month you are between weeks of pregnancy.

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Table of Contents

How to Convert Pregnancy Weeks into Months

You are pregnant and have started your check-ups with the gynecologist and/or obstetrician. They inform you that you are already 9 weeks pregnant and in your head, you start calculating, but you can't figure out how many months that is.

How can you know how many months you are? Using a pregnancy week and month calculator or by doing a manual calculation that we will now explain with two tables.

The first ones are simple to calculate, but as the pregnancy progresses, things get a bit more complicated. For this, we provide you with the following equivalence tables.

Table for Calculating Pregnancy Months

1 month of pregnancy

Weeks 1 to 4

2 months of pregnancy

Weeks 5 to 9

3 months of pregnancy

Weeks 10 to 13

4 months of pregnancy

Weeks 14 to 18

5 months of pregnancy

Weeks 19 to 22

6 months of pregnancy

Weeks 23 to 27

7 months of pregnancy

Weeks 28 to 31

8 months of pregnancy

Weeks 32 to 35

9 months of pregnancy

Weeks 36 to 40

Table for the End of Pregnancy Months

End of month 1

4 weeks + 3 days

End of month 2

8 weeks + 5 days

End of month 3

13 weeks + 1 day

End of month 4

17 weeks + 4 days

End of month 5

21 weeks + 6 days

End of month 6

26 weeks + 2 days

End of month 7

30 weeks + 4 days

End of month 8

35 days

End of month 9

40 days

Summary of Each Pregnancy Week

Now we will briefly tell you what happens each month, although if you want more detail, we recommend reading the detailed article about the pregnancy weeks.

As general advice, it's important to remember that you should not drink alcohol, smoke cigarettes, or take any other drugs.

Our idea is to help you with general information, but you should always verify the information with your doctor. Make a list of your questions and take them with you so you can discuss them with the professional treating you.

First Month

If you count from the first day of your menstruation, we are talking about the first to the 4th week of pregnancy.

Many times this month can go unnoticed, especially if you are not intentionally expecting a baby.

You may feel a bit tired, notice that you have a missed period, or even have spotting a few days before your expected menstruation date: this is normal and is due to the process of embryo implantation in the endometrium.

This month you may notice an increase in vaginal discharge and also that you have a greater sense of smell.

Second Month

This second month goes from week 5 to week 9.

Your baby's heart begins to beat, the ears and eyes start to form.

Hormonal changes begin to be noticeable: nausea starts, your breasts become more sensitive, you experience drowsiness or easy fatigue, and your urinary frequency increases.

Third Month

By this month, the embryo becomes a fetus. All organs are formed and begin to develop.

Your breasts continue to grow, the areola and nipple become darker. It is advisable to wear comfortable and loose clothing.

Fourth Month

The baby's eyes are already formed but remain closed, it is covered with a fine hair (called lanugo) and your little one measures approximately 15 centimeters.

Many good things happen this month: first, the risk of losing the pregnancy has significantly decreased, and second, the nausea is almost completely gone and the urge to sleep everywhere has diminished.

You may start to experience some difficulty evacuating (constipation), so maintaining a proper diet with fruits and vegetables could be advisable.

Another change you will notice is that your gums may be sensitive and bleeding. It's a good time for a dental check-up.

Fifth Month

You have started the fifth month, the uterus is now at the level of the navel and your baby makes energetic movements.

Gastric discomforts such as heartburn may begin.

The breasts are tense and increasingly sensitive. It is very important that you pay attention to your nipple, as some women have inverted nipples, which makes breastfeeding difficult, if so, tell your doctor.

Varicose veins begin to appear, it is important that you rest your legs up high and get used to sleeping on your left side, as this prevents pressure on the venous return.

Sixth Month

Your baby is now opening its eyes! It can even perceive light, eyebrows and eyelashes are formed, it responds to stimuli with music and already has a sleep activity pattern.

You experience mood swings, very much in relation to all the hormonal activity generated by the placenta.

The volume filtered by the kidney increases, so the urge to urinate increases, compounded by the pressure the belly exerts on the bladder.

The melanocytes (cells related to pigmentation) are more sensitive and the cloasma or melasma gravidarum (dark patch on your cheeks) may appear. You must permanently protect yourself from the sun.

Seventh Month

This month starts in week 28 of pregnancy.

Start preparing the baby basket! Although the baby is not yet ready to come out, sometimes it may come early and from this month that could happen.

In this month, the lungs are expanding, the skin becomes thicker and stops being transparent. The baby measures about 38 centimeters.

The uterus has significantly increased, occupying part of the thoracic cavity, which occasionally makes breathing difficult, and back pain also begins to appear.

Stretch marks have begun to manifest. It is very important that you stay well hydrated.

In this month you can start attending psychoprophylactic childbirth courses: these help you clarify doubts, teach you how to manage pain when contractions appear, you do breathing exercises to improve stress and to oxygenate your baby well, plus they will teach you exercises for your pelvic musculature, strengthening it and thus helping you prepare for the moment of childbirth.

Eight Month

The baby has gained weight (and so have you!), occupies the entire uterus and decreases its movements because it no longer has the same space. Its brain continues to develop.

The fatigue returns and will accompany you until the last month of pregnancy. The legs swell a bit and there is back pain.

Remember to monitor both your baby's movements and your blood pressure, between the 7th and 8th month, there is a risk of preeclampsia.

Ninth Month

You and your baby are about to meet! It now measures about 46 centimeters and its stomach and intestines are starting to function.

There may be urinary incontinence, as your baby is in a cephalic position, meaning its head is engaged in the pelvis.

You have already passed week 36, in about two weeks you will be face to face.

Bibliographic References

  • World health organization. Whoint. [Online]. Available at:
  • MSD Manual Professional Edition. MSD Manual. [Online]. Available at:
  • Sadler T. Langman: Medical Embryology. Buenos Aires: Editorial Médica Panamericana; 2004.
  • Navas Hernaldo A. The attention of childbirth by the psychoprophylactic method. Colombian Journal of Obstetrics and Gynecology. 1967;18(4):249-254.
  • Sánchez Á, Vázquez C, Andeyro García M. Guide to nutrition for pregnant women. 2015. Available at:
MD Katiuska Ríos Calderón
Doctor of Medicine and Surgery from UCLA. Specialized in Gynecology and Reproduction. Subspecialized in Endocrine Gynecology and Climacteric.
Dr. Katiuska Ríos Calderón holds a degree in Medicine from the Universidad Centr... Read more »

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