Week 20 of pregnancy (Days 140-146)

Your growing baby now measures between 15.2cm and 15.9cm from crown to rump and weighs approximately 255g. Around this week you will have your Anomaly Scan.

Your Baby

The fetus now measures between 15.2cm and 15.9cm from crown to rump and weighs approximately 255g. Vernix caseosa continues to develop and cover the entire body. This oily white substance protects the fetus from the effects of prolonged immersion in amniotic fluid and also helps with the birthing process.

The fetus continues and increases the frequency of swallowing, preparing the digestive system for after birth. Amniotic fluid is taken in through the mouth and the water content is absorbed, the remaining fluid moves into the large intestine. When amniotic fluid is swallowed, the fetus is able to taste the flavours of foods that you eat. Muscular development is continuing at a rapid rate now.

This period of pregnancy sees the most fetal activity due to a combination of sufficient skeletal and muscular development to allow complex movements and a large amount of amniotic fluid and available space in the uterus.

Your Body and Symptoms

You may find that you are becoming breathless more easily now. This is perfectly normal and is a consequence of your uterus pushing upwards against your diaphragm, leaving your lungs less room to expand.

Constipation is a common problem during pregnancy. Whilst eating a high fibre diet can help, taking supplements containing iron may actually make the problem worse. If you are concerned that iron supplements are causing constipation, do not stop taking them, but you should talk to your doctor or midwife to work out a solution. Lower abdominal pain is also common at this stage of pregnancy and is the result of the ligaments that support the uterus being stretched as it swells. Sudden movement may aggravate the pain, so avoid them where possible. You may find it helpful to use cushions for support when sitting or sleeping, but remember to avoid lying flat on your back.

Eating a healthy diet is important throughout pregnancy, but eating a varied diet can also benefit your baby. Now that the fetus is swallowing amniotic fluid, it is able to taste the flavours of any foods you eat. Eating a varied diet will help to develop the taste buds and prepare your baby to be receptive to a wide range of foods.

Symptoms to Watch Out For

At this time in the pregnancy there is often a sense of wellbeing and an absence of symptoms. However there may be troublesome aches and pains in the bones and muscles. These come and go.

There should be no bleeding or significant abdominal pain. The fetal movement may be felt later with a first baby than if you have had one before. The sensation starts as initial flutterings and develop gradually into discrete movements.

Your Care on the NHS

The NHS offer an anomaly scan between 18 and 22 weeks. A better and more detailed view of the baby will be seen at 20 to 22 weeks. This provides better detail about organs such as the heart. If the baby is not in an ideal position the sonographer may find it difficult to assess the full detail and you may be asked to move around or come back later. If the sonographer has any difficulty or there are abnormal findings then you will be asked to return to see a specialist doctor. After this scan you will have an appointment with the midwife or, if there are any problems, the consultant.

Private Care Available

If you want additional advice you can refer yourself to a private clinic. There you can have an appointment with a midwife, specialist doctor and you can have a high quality ultrasound scan. If you do not have confidence in the NHS scan for whatever reason it can be repeated with an anomaly scan. In a private clinic there should be more time, often better equipment and access to highly skilled expertise. If you have had a previous late miscarriage or carry twins then a cervical scan is readily available.

Explore other weeks

Week 5 of pregnancy (Days 35-41)

The embryo is approximately 1.3mm from the crown of the head to the rump but is very difficult to see and measure at this stage using ultrasound.

Learn more

Week 6 of pregnancy (Days 42-48)

Facial features continue to develop during this week, with tiny pits forming where the ears will eventually be. Nostril openings begin to appear along with dark spots where your baby’s eyes will be.

Learn more