18 Weeks Pregnant: Your Baby's Development

This week, your little one is developing a unique characteristic: fingerprints. Pads of fat accumulating on the fingertips and toes will turn into distinguishing swirling lines.

The developing digestive system has also been going through its paces for several weeks already. Your baby swallows amniotic fluid, which makes its way through the stomach and intestines. That fluid will combine with dead cells and secretions in the intestines to form meconium — a black, tarry substance you'll see at the very first diaper change.

At around 18 weeks, your baby’s ears will begin to stand out from of the sides of the head and may even begin to register sounds, while at 18 weeks, the gall bladder may begin to work to digest nutrients .

The Size of the Fetus at 18 Weeks Pregnant

When you’re 18 weeks pregnant, the fetus is around the size of a sweet potato.

The illustration below shows how things may be looking inside your belly this week:

Baby at 18 weeks pregnant


Mom's Body at 18 Weeks Pregnant

If this is your first pregnancy, you be wondering if you can feel the baby move at 18 weeks pregnant, and you may feel the baby begin to move inside your belly sometime soon. This fluttering feeling is known as quickening.

As your baby gets bigger, you may notice stronger movements and maybe even kicks in the weeks to come. Because each mom-to-be is different, you may feel this movement earlier (this is common if this is not your first baby) or in some cases even later. So, even if you don’t feel any movement at 18 weeks pregnant, there is no need to worry.

Your body is going through a lot of circulation changes, such as increased blood volume and rapidly expanding blood vessels, which can cause your blood pressure to drop. This can leave you feeling lightheaded if you’re not getting enough blood flow to your head and upper body.

You may also notice around 18 weeks that your feet are getting bigger. A part of this is due to swelling caused by water retention, known as edema, which can occur from the second trimester onward.

Hormones also play a part in growing feet. The pregnancy hormone relaxin, which relaxes your pelvic joints so your baby can fit through the birth canal, loosens the ligaments in your feet, causing the foot bones to spread. You can relieve the swelling with a footbath of cool water and by keeping your feet raised; don’t worry (and have fun!) if you need to head out shoe shopping for a bigger size.

If you’re wondering how many months pregnant you are at 18 weeks, the answer is you have probably now just turned 5 months pregnant.

18 Weeks Pregnant: Your Symptoms

At 18 weeks pregnant, here are some of the symptoms you may be experiencing:

  • Dizzy spells. Your heart is working 40 to 50 percent harder than it did before you were pregnant. This effort, combined with the pressure of your growing uterus on blood vessels, can occasionally leave you feeling faint, particularly when you get up quickly. Be sure to rest frequently. Lie down on your side when you feel faint or dizzy. Low blood sugar can also lead to wooziness. Resting, lying down on your side, or eating a piece of fruit will help boost blood sugar levels and settle dizzy spells.

  • Mini moves. Most women first feel their little one's movements between 16 and 20 weeks. Your baby is still small, so at around 18 weeks pregnant, it'll be more of a gentle flutter than a forceful kick in your belly.

  • Leg cramps. You may find that leg cramps start to strike at 18 weeks pregnant, usually at night. Try to stretch your calf muscles before bed and stay hydrated. A warm bath, hot shower, or a massage may help, too.

  • Nasal problems. Thanks to a surge in hormones and increased blood volume during pregnancy, which causes mucous membranes to swell up, you might experience nosebleeds and congestion.

  • Aches and pains in the back. Your growing belly and hormonal changes can lead to aches and pains in your lower back area.

18 Weeks Pregnant: Things to Consider

  • Follow a diet rich in omega-3 fatty acids. Getting the nutrients you and your baby need is important, and omega-3 fatty acids are a crucial part of a healthy diet. Omega-3s help your little one’s nervous system develop, and some research shows that they may also help boost your immune system and reduce the symptoms of depression. Look for foods that are rich in this nutrient, like salmon or other fatty fish, or get your omega-3s from vegetarian sources like flaxseed, broccoli, or walnuts. You can learn more about nutrition during pregnancy in our downloadable pregnancy guide.

  • Increase your calorie intake healthily. You'll need some extra calories to support your growing baby, but you don’t actually need to eat for two. Once you reach the second trimester, this could be an extra 300 calories — half a sandwich and a glass of skim milk, say — on top of an average 2,000 calories a day. You can learn more about how to plan a healthy pregnancy diet.

  • You may notice that everyone, from your mother-in-law to complete strangers, feels compelled to offer advice about your pregnancy. Although unsolicited opinions can be annoying, try to take them in stride. You don't have to explain yourself to anyone. A simple "Thanks, I'll keep that in mind" should do the trick. Try to remember that people mean well, and they're excited for you. You may even find some of the parenting tips you get are actually helpful.

  • In rare cases, the mid-pregnancy ultrasound reveals a problem associated with the placenta. Your healthcare provider will tell you if he suspects either placenta accreta or placenta previa and will be able to advise you on what care you will be given to lower any risks associated with either condition.

18 Weeks Pregnant: Ask Your Doctor

  • Is your baby’s movement and position on track at 18 weeks pregnant?

  • Can you schedule an ultrasound exam to determine the sex of your baby?

  • What are the risks and benefits of any genetic testing that may be offered in the coming weeks?

  • Is amniocentesis recommend for you?

  • Is it safe to travel at this point in your pregnancy?

18 Weeks Pregnant: Your Checklist

  • Plan a “babymoon” getaway, if your healthcare provider gives you the OK.

  • Start collecting books to read to your baby.

  • Compile a list of possible baby names for your little one, and check out our Baby Name Generator for inspiration.

  • Sign up for even more weekly pregnancy tips:

How we wrote this article
The information in this article is based on the expert advice found in trusted medical and government sources, such as the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists. The content on this page should not replace professional medical advice. Always consult medical professionals for full diagnosis and treatment.