At five months pregnant (roughly weeks 17 through 22), your baby is about 6 to 11 inches long and weighs somewhere between 5 and 15 ounces, depending on the exact week. That’s a huge range because growth accelerates rapidly during this stretch. Your baby essentially triples in weight over the course of a single month.
Size Week by Week
The fifth month of pregnancy spans weeks 17 through about 22, and your baby’s size changes noticeably each week. Here’s what to picture:
- Week 17: About the size of a navel orange
- Week 18: About the size of a pomegranate
- Week 19: About the size of a grapefruit
- Week 20: About the size of a mango
- Week 21: About the size of a cantaloupe
- Week 22: About the size of an eggplant
At the start of month five, your baby fits in the palm of your hand. By the end, they’re closer to the length of a small doll. This is one of the fastest growth periods in the entire pregnancy.
What’s Developing at This Size
Your baby isn’t just getting bigger. Around week 18, the ears mature enough that your baby may begin to hear sounds. That includes your voice, your heartbeat, and the rumble of your digestive system. By week 19, a greasy, cheese-like coating called vernix starts forming on the skin. It acts as a protective barrier against the amniotic fluid, preventing the kind of chapping and irritation you’d get from soaking in liquid for months.
By week 21, a layer of fine, downy hair covers the entire body. This hair, called lanugo, helps the vernix stick to the skin. It will shed before or shortly after birth. Your baby is also building fat stores during this period, which is why the weight gain picks up so dramatically. Earlier in pregnancy, most of the growth was structural: bones, organs, and limbs taking shape. Now the body is filling out.
When You Start Feeling Movement
Month five is when most people feel their baby move for the first time. If you’ve been pregnant before, you may have noticed fluttering as early as 16 weeks. For a first pregnancy, it’s common not to feel anything until around 20 weeks.
Those first movements, called quickening, don’t feel like kicks yet. People describe them as fluttering like a butterfly, tiny tapping or pulses, bubbles popping, small muscle spasms, or light rolls and tumbles. It’s subtle enough that you might confuse it with gas or digestion at first. Over the coming weeks the sensations get stronger and more distinct, and eventually you’ll be able to tell a kick from a stretch.
How Your Doctor Tracks Size
Around week 20, most providers schedule the mid-pregnancy anatomy scan. This ultrasound doesn’t just check for structural development. It also takes four key measurements to confirm your baby is growing on track: the diameter of the head, the circumference of the head, the circumference of the belly, and the length of the thigh bone. These numbers are compared against standard growth curves to estimate weight and flag anything that might need closer monitoring.
Your provider will also start measuring your fundal height at around 20 weeks. This is a simple tape-measure check from your pubic bone to the top of your uterus. At 20 weeks, the top of your uterus typically reaches your belly button. From this point forward, the measurement in centimeters roughly matches your week of pregnancy, give or take about 2 centimeters. So at 22 weeks, you’d expect a fundal height of about 20 to 24 centimeters. It’s one of the simplest and least invasive ways to spot potential growth issues between ultrasounds.
The Halfway Mark
Week 20 is the official halfway point of pregnancy, and it tends to feel like a milestone for good reason. Your baby has all major organs in place, is actively moving, and is developing the senses that will help them interact with the world after birth. The anatomy scan at this stage gives most parents their most detailed look at their baby so far.
By the end of month five, at 22 weeks, the pregnancy reaches the very earliest edge of what medicine considers potentially viable outside the womb. Survival at 22 weeks remains difficult, with about a 41% survival rate among infants who receive active treatment, but that number has climbed significantly in recent years as neonatal care has advanced. At 23 weeks, survival improves to roughly 58%. These numbers reflect just how much development still needs to happen, but they also show how far along your baby already is by the end of this month.