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During its 16th week of development, a fetus will be starting to form facial expressions, and its nervous system will be growing.

The fetus weighs around 2 and a half ounces (oz), and you may be starting to feel fetal movement.

This feature is part of a series of articles on pregnancy. It explains the symptoms of each stage of pregnancy, what to expect, and insights into the development of your child.

The other articles in this series can help you through each week of pregnancy.

First trimester: fertilization, implantation, week 5, week 6, week 7, week 8, week 9, week 10, week 11, week 12.

Second trimester: week 13, week 14, week 15, week 17, week 18, week 19

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You may be experiencing a “pregnancy glow” due to increased blood flow beneath the skin.

On reaching the 4th month of pregnancy, you might experience increased sexual libido as a result of surging pregnancy hormones.

This does not occur in all women.

As the womb grows and moves up in the torso, the pregnancy bump will become more pronounced. Women at this stage of pregnancy should also find that the urge to frequently urinate is easing off.

Week 16 might also see the start of the “pregnancy glow” that many people associate with having a baby. This is the result of increased blood flow in the skin and higher levels of oil production in the skin glands. These mechanisms occur because of the spike in hormonal activity.

This extra production of oil can cause acne. During pregnancy, avoid acne medication. Instead, use fragrance-free face wash and oil-free moisturizer on a daily basis.

Hormones can also stretch the veins, leading to varicose veins. You may also experience cramps and sharp pains in the leg. Exercising and stretching the legs during the day can help relieve these symptoms.

Your next antenatal appointment should be taking place soon.

The doctor will review options for genetic screening on the fetus. This could involve simple blood tests or even amniocentesis. In addition to genetic screening, blood tests can identify neural tube defects, such as spina bifida.

A doctor may carry out amniocentesis between weeks 15 and 18 to diagnose any chromosomal anomalies. It can take place at any time, but your doctor will most likely perform the test around this gestational age.

Amniocentesis is a test that involves using a needle to drawing out some of the amniotic fluid that surrounds a fetus. This can help rule out chromosomal abnormalities present in an infant, such as Down’s syndrome and trisomy 13 and 18.

The doctor extracts and tests a small amount of amniotic fluid. Amniocentesis carries a miscarriage risk of between 1 in every 500 and 1000 cases.

A physician will often recommend genetic screenings for high-risk pregnancies, such as those in women over the age of 35 years. Your doctor will review the available blood tests and compare them with the results of amniocentesis to help you reach a comfortable decision.

Your physician may also want to discuss choosing prenatal and childbirth classes. They may also want to review any possible pain of the round ligaments in the abdomen or hip you may be experiencing.

The doctor might also discuss precautions for preterm labor.

At week 16, your fetus is around 5.3 inches from crown to rump. This is roughly the size of a lemon or avocado. They will weigh roughly 2.5 ounces (oz.).

The fetus is at the start of a growth spurt that will see it double in size over the next month.

It may also start moving and can even grip the umbilical cord at this stage. The nervous system is still developing, and the fetus is starting to flex the muscles in their limbs.

A fetus will start forming facial expressions at this stage, although it cannot yet control them. If you could see the fetus, it might appear to frown or squint at points.

The eyes and ears of the fetus will now have fully moved from the side of the head and will much more closely resemble their final appearance.

As with earlier weeks, you will soon find out that there are many lifestyle modifications that need to be made during pregnancy and after delivery.

General health

In the second and third trimesters, a woman who is pregnant should no longer lie flat on her back for long periods of time.

Lying on the side promotes better blood flow to the fetus and may also improve back and hip discomfort. Pregnancy pillows are available to help ease the process of lying on your side for long periods of time.

There is a selection of pregnancy pillows available for purchase online.

Avoid alcohol, smoking, and all other toxic or illicit substances at this time.

Make sure that your doctor knows about any ongoing medications you may be taking. If it is likely to interfere with the pregnancy, they may consider reducing the dosage or changing the type of medication you take.

You may also benefit from a specialized exercise regimen during pregnancy.


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Eating well can lead to a safer pregnancy and a healthier infant.

Follow a balanced, nutritious diet during any stage of pregnancy, as well as placing a focus on staying active.

The fetus is starting to grow rapidly and requires more energy at this point in pregnancy. It is recommended that you consume an extra 300 calories every day.

Avoid increasing the size of each meal and instead eat a snack in addition to your usual intake. Examples of appropriate snacks include:

  • an apple with one tablespoon (tbsp.) of nut butter
  • one cup of broth
  • a hard-boiled egg
  • a handful of almonds and a cheese stick

While the physician overseeing your pregnancy may have prescribed supplements to boost levels of certain vitamins and minerals, this will not provide all of the nutrients necessary for you and the fetus.

Be sure to eat plenty of leafy greens, which support digestion, as well as foods that contain high nutritional value, such as fruit and nuts.

Avoid the following foods during pregnancy:

  • raw meat
  • cold cuts from a deli
  • smoked seafood
  • fish that contain mercury, such as shark and swordfish
  • soft cheeses
  • raw shellfish
  • raw eggs
  • unpasteurized milk
  • patês and meat spreads

Be sure to wash any vegetables in a meal thoroughly.

Other concerns

If you notice any unexpected symptoms, contact your physician immediately. These can include:

  • leaking vaginal fluid
  • vaginal bleeding or passage of tissue
  • faintness or dizziness
  • low blood pressure
  • rectal pressure
  • shoulder pain
  • severe pelvic pain or cramping

MNT is here to support you throughout your pregnancy.