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    18 weeks pregnant: Your guide to this week of your second trimester

    Updated 21 July 2023 |
    Published 24 February 2019
    Fact Checked
    Medically reviewed by Dr. Angela Jones, Obstetrician and gynecologist, attending physician, Jersey Shore University Medical Center, New Jersey, US
    Written by Kate Hollowood
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    From feeling your baby move to insomnia, here’s the lowdown on being 18 weeks pregnant.

    At 18 weeks pregnant, you’re almost midway through your pregnancy and may be wondering what’s next. Excitingly, there’s a good chance that this week could be the first time you feel your baby moving, if you haven’t already. 

    Read on to learn more about the changes that are happening to your body and baby this week. We also have advice from a Flo expert on the pregnancy symptoms to be mindful of as you approach that magical midway point.

    Your baby at 18 weeks pregnant

    Growing hair

    This week, your baby is starting to grow soft, fine hair called lanugo. This fuzz-like hair covers their body, growing wherever there is a hair follicle. This might sound strange, but it serves an important purpose. Essentially, it acts as a protective layer to help keep your baby warm. Usually babies shed this hair before they are born, but if they still have it when they’re born, it will soon disappear on its own. 

    Developing a digestive system

    Your baby’s digestive system has also started to work. This vital system will help your baby pass their first poop within 24 to 48 hours after birth. Called meconium, it will be a sticky, dark-green substance that’s thicker than normal poop. 

    How big is a baby at 18 weeks?

    Length (crown to heel): 22 cm or 8.7 in.

    Weight: 223 g or 7.9 oz. 

    Size: Equivalent to a cucumber

    All measurements are approximate and vary within the normal range.

    Your body at 18 weeks pregnant

    You might feel your baby move for the first time

    This can be a joyful week for some pregnant women, as you may feel your baby move for the first time. This can be one of the most exciting second-trimester symptoms, and it usually happens between 16 and 20 weeks pregnant

    This early movement is often called “quickening,” and it might feel quite subtle, like a bubbling, fluttering, or slight shift in your belly. It can be helpful to watch for patterns and get to know your baby’s frequency of movement. 

    If you haven’t felt anything yet, there’s no need to panic. It’s normal to not notice this change at 18 weeks. In fact, for first-time pregnancies, it’s common not to notice quickening until around 20 weeks. But if you’re worried, there’s no harm in talking to your health care provider. Just so you know what to expect, you should definitely feel some movement by 24 weeks, and by the third trimester, you should feel at least 10 movements in two hours. 


    Have you heard of insomnia? This frustrating symptom is when you are struggling to get enough sleep, to the point that it disrupts how you function or feel

    “Insomnia is common throughout pregnancy and can increase during the course of pregnancy,” explains Dr. Jenna Beckham, obstetrician and gynecologist, WakeMed, North Carolina, US. In fact, one study found that 60% of pregnant people experience insomnia by late pregnancy. Meanwhile, another survey found that 78% of pregnant women reported disturbed sleep of some kind. So if you find yourself wide awake at 4 a.m., take some comfort in knowing that you’re definitely not alone.

    There are a number of different causes of insomnia during pregnancy, from your changing hormone levels to natural feelings of anxiety about parenthood and what’s next. During the second trimester in particular, changes like leg cramps, swollen feet, lower back pain, nasal congestion, and heartburn can all have a negative impact on sleep. No fun!

    The good news? There are some things you can do to help you get a restful night of sleep. Practicing good sleep hygiene, like having a fixed wake-up time, can help to ease insomnia. And if you think medication could help, be sure to speak to your doctor for their advice. Dr. Beckham advises trying melatonin first and then an antihistamine, such as doxylamine or diphenhydramine, if that’s not effective. Just remember to speak to your health care provider before taking any medication or supplements during pregnancy. 

    Finally, if you’re dealing with anxiety, know that help is out there, and you don’t need to suffer in silence. Self-care activities like mindfulness, exercise, and journaling can help, as can talking therapy. If anxiety is having a big impact on your life, you may want to discuss trying some medication with your doctor. 

    Your questions answered

    Is 18 weeks considered the same as 5 months pregnant?

    At 18 weeks, you’re about midway through your fifth month of pregnancy. You’ll then start your sixth month of pregnancy at 21 weeks. But before that, you’ll have a major milestone to celebrate! At 20 weeks, you’ll be considered halfway through your pregnancy, meaning it won’t be long before you can start the countdown to your due date

    What should I be feeling at 18 weeks of pregnancy?

    At 18 weeks pregnant, your growing baby bump might make you feel a bit clumsier than normal, and you’ve probably noticed that your breasts are looking bigger, too. You may also have noticed feeling dizzy when you get up too suddenly, thanks to your blood pressure being a bit lower than usual. This might feel scary sometimes, but rest assured that these are all normal, if frustrating, parts of pregnancy. Experiencing these symptoms doesn’t mean there’s anything wrong with you or your baby.

    As you continue into your second trimester, you will hopefully be feeling more energetic, but it’s also perfectly normal to still experience earlier pregnancy symptoms like nausea at this stage. 

    Lots of women find it hard not to compare their pregnancy to others’, but remember that everyone is different. “Pregnancy is a very individual experience,” explains Dr. Beckham. “Each pregnant person will have a unique physical and emotional journey during pregnancy. There is no particular way that anyone should feel.” So try to relax and remember that your body will do its own, beautiful thing.

    What should I avoid at 18 weeks pregnant?

    You’re already on track; the things you should avoid at 18 weeks pregnant are no different from previous weeks. “There are no specific avoidances unique to 18 weeks of pregnancy,” explains Dr. Beckham. 

    But just in case, let’s do a recap of some of those things. From the first trimester onward, you should avoid activities that involve lying flat on your back. This position can cause the weight of your bump to press on a main blood vessel to your heart, which can make you feel faint. If you’re not sure whether an activity is safe during pregnancy, remember to always check in with your doctor first. 

    Some of the other key things to avoid throughout your pregnancy include smoking, caffeine (or no more than 200 mg per day), and alcohol. You should also avoid certain foods, including: 

    • Unpasteurized or soft ripened dairy products (e.g., goat’s cheese, brie, gorgonzola, and unpasteurized milk and cream) 
    • Certain types of meat, including raw or undercooked meat, liver and liver products, all types of pâté (including vegetarian pâté), and game meats such as goose, partridge, and pheasant
    • Certain types of fish, including swordfish, marlin, shark, and raw shellfish
    • More than two portions a week of oily fish like salmon, sardines, trout, mackerel, and herring, and more than two portions a week of tuna steak (or four cans of tuna)
    • Raw or partially cooked eggs

    Finally, the idea that you need to “eat for two” during pregnancy can be misleading. In your second trimester, you should eat an extra 340 calories a day and a little more than this in the third trimester. This could mean adding one or two healthy snacks to your plate each day, such as hummus and pita bread. So now’s a perfect time to try out some new recipes! 

    Want to know more?

    Download the Flo app for tailored insights throughout your pregnancy

    18 weeks pregnant checklist 

    Consume vitamin D

    Your baby needs vitamin D to develop healthy bones, teeth, eyesight, and skin, so it’s important to make sure you’re getting enough throughout your pregnancy and when breastfeeding. The best sources of vitamin D are sunlight, fortified milk, and fatty fish such as salmon and sardines (just be careful to eat salmon and sardines in moderation, as we explained above). Especially during the winter months, it can be a good idea to take a vitamin D supplement (10 mcg) every day. Just be sure to always speak to your health care provider before starting any new supplements or medication.

    When to consult a doctor at 18 weeks pregnant

    During your second trimester, you might be having prenatal appointments every four weeks. However, this will depend on where you live and what your doctor decides is right for you and your baby. At these appointments, your doctor will check your vitals, like your blood pressure and weight, as well as track your baby’s growth and heart rate

    You don’t need to wait until your appointment if you have any concerns or questions about your pregnancy. However, at 18 weeks pregnant, you should contact your doctor immediately if you experience: 

    This isn’t an exhaustive list and just an example of some of the changes you should look out for. Some of these can be a sign of miscarriage or other health complications, so it’s essential that you speak to your doctor about the best next step for you. And if you’re ever worried about any other symptoms you experience during pregnancy, then don’t hesitate to reach out to your health care provider. 

    18 weeks pregnant: The takeaway

    You may be focusing hard on feeling any baby movements at 18 weeks pregnant, which can be fun and anxiety inducing at the same time. If you haven’t felt anything yet, try to take your mind off it. You’ll feel those first little kicks before you know it. 


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    History of updates

    Current version (21 July 2023)

    Medically reviewed by Dr. Angela Jones, Obstetrician and gynecologist, attending physician, Jersey Shore University Medical Center, New Jersey, US
    Written by Kate Hollowood

    Published (24 February 2019)

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