The 18th week of pregnancy

A lot is happening for you and your baby in week 18. Here you can read all about the baby and your body in the 18th week.

Pregnant mum stroking her belly with her young daughter

Your heart is now working 40 to 50 percent harder than normal because of the increased blood volume during your pregnancy. You may feel lightheaded and dizzy. Discuss any changes in your physical health with your midwife/ doctor.

As ligaments stretch and adjust with your growing baby, you may experience a stretching pain in the form of a twinge in your abdomen.

Your baby’s development at 18 weeks of pregnancy

Your baby is already the size of a sweet potato. Length from head to toe is about 15 cm and your baby weighs between 125 and 200 grams.

Your baby's hands and feet are now fully developed. And they even have tiny, soft fingernails and toenails.

Your baby can move their arms and legs. Through these movements their brain is stimulated with sensory experiences. Your baby has already developed some reflexes. By the time of birth, your baby has almost all the reflexes they need.

The development of the lungs also progresses considerably in the 18th week of pregnancy. Your baby also swallows amniotic fluid which strengthens the maturing digestive system. Amniotic fluid and old cells pass from the stomach into the intestinal tract, where meconium is formed. This is the black sticky, tar-like substance that babies have as their first poos!


*The height and weight figures are average values and cannot be applied to individual cases. Every baby develops individually.


1. Marshall, J.E. and Raynor, M.D. (2020) Myles Textbook for Midwives. 17th ed. London: Elsevier

2. Vitamins, supplements and nutrition in pregnancy Vitamins, minerals and supplements in pregnancy - NHS (

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