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

    Updated 28 August 2023 |
    Published 24 February 2019
    Fact Checked
    Dr. Angela Jones
    Medically reviewed by Dr. Angela Jones, Obstetrician, gynecologist, and attending physician, Jersey Shore University Medical Center, New Jersey, US
    Flo Fact-Checking Standards

    Every piece of content at Flo Health adheres to the highest editorial standards for language, style, and medical accuracy. To learn what we do to deliver the best health and lifestyle insights to you, check out our content review principles.

    From sleep changes to your birth plan, here’s the lowdown on being 20 weeks pregnant.

    By 20 weeks pregnant, you might have started to feel your bump developing. While some people “show” sooner than others, starting to see the physical signifiers of your pregnancy can be exciting but also a little daunting. You’re preparing for a major life change, after all. 

    At 20 weeks pregnant, you may also feel a little bit more like yourself again. Symptoms like fatigue or nausea may have subsided. You might have heard pregnancy nausea referred to as morning sickness, but pregnancy sickness can strike at any time – morning, noon, or night. Alongside changes in your symptoms, you may also have your anatomy scan either this week or in the coming weeks, when you might be able to find out the sex of your baby. This can add a new level of excitement.

    Although you’re about halfway through your pregnancy now (as pregnancy is considered to be full-term if your baby is born between 39 weeks and 40 weeks and 6 days), there may still be some new things to consider as your body continues to change and your baby grows. So, here are some of the things to think about at 20 weeks pregnant, with advice from a Flo expert. 

    Your baby at 20 weeks pregnant

    Producing antibodies

    Around now, your baby is producing antibodies that will protect them from getting sick. The two types of antibodies that your baby is producing are called immunoglobulin G (IgG) and immunoglobulin M (IgM). This might sound science-heavy, but IgG and IgM have pretty simple jobs. IgG is responsible for fighting infections caused by bacteria and viruses, while IgMs are the first antibodies that your body produces after being exposed to new germs. Clever, right?

    Developing lanugo

    You may remember that at 19 weeks pregnant, your baby develops the vernix caseosa. This is a white, sticky layer (made of mostly water and proteins) that covers their skin to protect them from the amniotic fluid and help them to regulate their temperature. The vernix caseosa has to bind to your baby, and to help it do so, they develop lanugo at around 20 weeks. You can think of this as a soft, fine hair that covers your baby’s body. The lanugo helps to protect your baby and keep them warm. While many babies will shed these fine hairs before being born, some will be born with them. 

    How big is a baby at 20 weeks?

    Length (crown to rump): 25.7 cm or 10.1 in

    Weight: 331 g or 11.7 oz

    Size: Equivalent to a grapefruit

    All measurements are approximate and vary within the normal range.

    At week 20 of pregnancy, the baby is around 25.7cm long, equivalent to the size of a grapefruit