16 weeks pregnant: Pregnancy Symptoms & Baby Development
Find out what to expect from every week of your pregnancy.
16 weeks pregnant is how many months?
Month 4 (Trimester 2)
Baby development at 16 week
Vitamin D

What’s happening in your body?
Your baby is now the size of an avocado, and around 11.6cm in length. He or she will weigh around 100g. The circulatory system is now starting to run, and can pump over 28 liters of blood a day.
Around now, your baby may start flexing their arms and fingers. Their hands may even be able to meet, form a fist, and hold each other. As your baby’s nervous system continues to develop, their range of movements will also progress.
Your baby may also be able to recognize your voice. Studies have shown that babies who hear a song while in the womb react to the same song when it’s sung after they’re born. Choose your lullabies wisely.
While they’re beginning to make facial expressions, they can’t control them yet. More importantly, your baby is gearing up for a tremendous growth spurt, more than doubling in weight over the next few weeks.


Pregnancy symptoms at 16 weeks
By now most mum-to-be are free of the unpleasant pregnancy symptoms of their first trimester. However, there are still uncomfortable symptoms that you can experience at 16 weeks, including:
- Continued breast growth and sensitivity
- Constipation Increased vaginal discharge
- Bleeding gums
- Varicose veins
- Back ache
Pregnant women have an increased risk of vitamin D deficiency and need to pay special attention to getting adequate levels. Taking a daily supplement protects your own health, as well as your baby’s.
If you have dark skin, your increased pigment affects your skin’s ability to generate vitamin D, making a daily supplement even more important. Women of South Asian, African, Caribbean and Middle Eastern descent who live in the UK are particularly at risk.
Sunlight creates vitamin D naturally, although take great care not to over-expose yourself to the sun. Between October and April, the body uses reserves left over from summer.
A few foods provide vitamin D, but these are limited. Oily fish, egg yolks and fortified foods are among the few dietary sources. In the UK many people find it difficult to get significant amounts from food alone.
Because of this, it’s recommended that all pregnant and breastfeeding women take a vitamin D supplement of 10mcg per day. This amount will provide enough for your own needs and help to build the stores your baby needs for the first 6 months of life.

THE SCIENCE BEHIND vitamin D
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Your baby is hungry for vitamin D as it’s essential to help bone development by regulating calcium and phosphate in the body. A lack of vitamin D can lead to conditions like rickets in children, and osteomalacia (bone pain) in adults. The good news is that, from early spring to the end of September, you should be able to get plenty of vitamin D from sunlight.