Pregnancy week 18: symptoms, baby size and tips
Pregnancy week 18 is often one of the most exciting of the whole second trimester. Your baby is now the size of a red bell pepper, their skeleton keeps hardening without stopping and, very importantly, for many mums this is the week they first feel their baby move. It’s a beautiful moment — let me walk you through it, as always ❤️.
If you’re coming from pregnancy week 17, you’re on a great track. And to have the whole path at hand, check out our pregnancy week by week guide.
What is pregnancy week 18?
As always, pregnancy weeks are counted from the first day of your last period (LMP), not from conception. In week 18 you’re about 16 weeks from fertilisation, entering your fifth month of pregnancy (weeks 18–21) and still right in the second trimester, which runs from week 13 to week 28.
You’re past the halfway point of this trimester, the one many women find easiest: you often have more energy, fewer symptoms and you start to enjoy the bump, which shows more every week. Your uterus is clearly above your pubic bone and your bump is starting to be quite visible.
Your baby’s first movements: the big sign of week 18
One of the most exciting things about these weeks is feeling your baby move for the first time. Although every pregnancy is different, it’s common for the first movements to be felt between weeks 18 and 22.
- If you’ve been pregnant before, you might already notice little flutters, bubbles or tickles that will soon turn into kicks.
- If it’s your first pregnancy, don’t worry if you feel nothing yet: the first movements usually arrive around week 20 or later.
These first movements are often felt like butterflies in your stomach, gas bubbles or a little fish moving around. As the weeks pass they’ll become clearer and stronger. If you still feel nothing, it doesn’t mean anything is wrong with your baby: every mum and every pregnancy has its own rhythm.
How is your baby developing in week 18?
Your baby is still growing at a dizzying pace. These are the highlights this week:
- Their skeleton keeps calcifying: the cartilage is turning into bone, especially in the arms, legs and spine. Their heartbeat is easy to pick up with a Doppler.
- Their nervous system matures: the neurons in their brain start to be covered with a substance called myelin, which speeds up signal transmission. Their brain keeps growing fast.
- Their hearing is sharpening: th
