Changes in the third month of pregnancy

The uterus grows and the mother's belly is now noticeable

In the third month of pregnancy some of the symptoms of pregnancy begin to ease. The mother feels a little better every day and it is likely that she will notice that her waist has enlarged a few centimetres.

Changes in the mother

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The physical unease begins improve. For most pregnant women, nausea stops completely that month, although for some women it can last longer, and sometimes morning sickness persists throughout the entire pregnancy.

If, in addition to the nausea, you keep vomiting excessively, you may have hyperemesis gravidarum, which is considered a serious condition and requires hospital treatment.

Other symptoms, such as emotional instability, breast enlargement and night cramps continue during this month.



Physical changes

  • Increased skin pigmentation occurs due to the hormonal effect. This increase occurs in areas such as the line from the abdomen to the belly button, the armpits, around the areolae (which become larger and darker), the perineum and on the inside of the thighs. It can also appear on the face, and is known as chloasma gravidarum. These spots cannot be avoided but their appearance can be attenuated by avoiding sun exposure or by providing good sun protection. They usually disappear after childbirth.

  • During this period, many pregnant women experience reflux and heartburn caused by the compression of the uterus. This pressure of the growing womb also affects the venous return from the lower part of the body, producing a feeling of heaviness in the legs.

  • An increase in salivation, called ptyalism or hyper-salivation, often occurs.

  • The uterus continues to grow and is now above the pelvis. This growth causes pelvic discomfort and weight gain, and the belly is now slightly noticeable. The average weight gain at this stage of pregnancy is 2 kg.


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Changes in the baby in the third month of pregnancy

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The size of the foetus at the end of this month is between 6.5 and 8 cm and it weighs between 13 and 20 g.

This month, the embryonic period ends and the foetal period begins. Most of the foetal structures are already formed and, from this point, it grows and develops.

The head of the foetus continues to be disproportionately large; it is almost the same size as the rest of the body. Facial features are becoming increasingly clear.

The foetus moves by stretching and contracting its arms and legs. Its heart rate ranges between 120 and 160 beats per minute.

Around week 11 and 12, the sex organs differentiate.



Dr. Miguel Ángel Herráiz
Head of the Gynaecology Service of Hospital Clínico San Carlos (Madrid)