18th Week Pregnancy: Symptoms, Baby Development, And Body Changes


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How Many Months Pregnant Are You At 18 Weeks?

At 18 weeks, you are in the second trimester and four-and-a-half months pregnant. Your energy levels will be slightly higher now, and you will start to feel your baby’s first moves.

Here, Momjunction explains more about fetal development and the changes that you experience in this week.

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How Big Is The Baby At 18 Weeks?

At 18 weeks, your baby is as big as a bell pepper (1), measures 5.6in (14.2cm) in length and weighs 6.7oz (190g) (2). Your baby’s growth continues with the development of different parts of the body.

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Baby’s Development At 18 Weeks

Here is how the baby’s body is developing in this week:

Body partsDevelopmental stage
SkinIs wrinkled and coated with a waxy substance called vernix. Fine hair called lanugo is also visible.
EarBones of the middle ear and nerve endings from the brain are developing, helping the baby hear clearly (3).
EyesThe retina is developing. It can respond to a beam of light.
BonesBegin to harden in the clavicles and legs.
NervesGets covered with a tissue coating called myelin (4).
FingersUnique fingerprints are formed.
LungsBreathing passages are being developed to form the bronchial tree (5).
NailsFinger and toenails are developed to the tip (6).
MouthSwallowing and sucking movements start. Some babies can also get hiccups.
Liver and pancreasProduce secretions (7).
GenitalsCan be seen through an ultrasound scan.

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[ Read: 17th Week Pregnancy ]

Fetal Movement In The 18th Week Of Pregnancy

The fetal movement can usually be felt between the 18th and 20th week (8). The movements might feel like a flutter, swish, or roll. Most women may not be able to identify the baby’s movements, also called quickening, and may mistake it for gas. As the baby grows, it becomes more active, and the movements inside are more prominent.

With the baby growing and possibly moving, you will also experience certain changes in your body at this time.

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Symptoms You Will Experience In The 18th Week Of Pregnancy

The common pregnancy symptoms that you may experience during the 18th week are:

  1. Weight gain: The ideal weekly weight gain at this time, according to your BMI, should be (9).
BMI>18.5 (underweight)18.5 – 24.9

(normal weight)

25 – 29.9


30 and higher (obese)
Weight /week1 ½ pound1 pound⅔ pound½ pound
  1. Frequent urination: The growing uterus puts pressure on the bladder, which increases the frequency of urination.
  1. Constipation: The progesterone hormone relaxes the muscles of the digestive tract. The food thus remains in the tract for a longer time so that maximum nutrients are absorbed into the bloodstream.
  1. Dizziness: The increasing size of the uterus compresses the blood vessels and limits the blood flow to the brain, causing fatigue or lightheadedness. Sometimes staying hungry for a long time can also contribute to lightheadedness. Make sure that you eat properly and drink water to keep the body hydrated.
  1. Backache: The growing uterus shifts the body’s center of gravity, exerting pressure on the lower back, causing backache.
  1. Stuffy nose: Hormonal changes can result in more blood flow to the mucous membranes, making them swell and soften, causing stuffy nose and congestion. Increased pressure on the veins in the nostrils can lead to nosebleeds.
  1. Leg cramps: The growing uterus causes compression of the blood vessels leading to leg cramps, usually experienced at night.
  1. Heartburn: The gastric fluids are pushed upwards to the esophagus as the stomach is pushed towards the diaphragm by the growing uterus.
  1. Trouble sleeping: With the backaches, hip pain, and leg cramps, you may have trouble sleeping. Using a pillow around the stomach and between the legs can offer some relief.
  1. Edema: Water retention in the body can cause swelling of the feet and hands.
  1. Varicose veins: Excess blood flow to the lower part of the body leads to swelling of the nerves in your legs, also called varicose veins.

Physical and emotional changes in the body at this time give away that you are pregnant. Read about them next.

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[ Read: 16th Week Pregnancy ]

Changes In The Body At 18 Weeks

Changes In The Body At 18 Weeks

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Physical changes

  • Enlarged breast: The breasts become swollen and tender, as the body preps them for breastfeeding.
  • Growing belly: The tummy protrudes, and you can feel the uterus between the pubic bone and the navel.
  • Linea nigra: The line gets darker due to pigmentation.
  • Stretch marks: The growing uterus stretches the skin, creating stretch marks on the belly.
  • Shinier hair: Change in hormonal levels reduces hair fall. The hair looks fuller and shinier.

Emotional changes

  • Mood swings, due to hormonal changes.
  • Weird dreams, due to pregnancy-related fears and anticipations.
  • Anxiety

The 18th week is more or less a safe zone for you and your baby, with few chances of a miscarriage. However, it cannot be entirely ruled out.

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Is There Any Risk Of Miscarriage At 18 Weeks?

At the 18th week of pregnancy, miscarriage is rare but the chances cannot be overlooked (10).

  • About 1 to 5% of pregnancy losses occur between the 13th and 19th week of gestation.
  • There is a 24% chance of pregnancy loss in the second trimester because of the chromosomal abnormalities such as trisomies 13, 18, and 21, sex chromosome polysomies, and monosomy X (Turner syndrome).
  • Structural abnormalities also cause pregnancy loss. It may be due to the amniotic band syndrome, neural tube defects, maternal exposure to teratogens or uncontrolled maternal diabetes at the time of conception.
  • Cervical insufficiency with painless cervical dilation, maternal history of thrombosis, maternal hypertension, and physical abuse can also lead to miscarriage during the second trimester.
  • Miscarriage can happen due to an infection such as bacterial vaginosis. This can need you to stay longer in the hospital for a dilation and curettage (D&C) procedure.

[ Read: 19th Week Pregnancy ]

Other causes of miscarriage include:

  • Immunity issues
  • Maternal hormonal abnormalities
  • Stress
  • Sexually transmitted diseases
  • Erratic lifestyle

If you suspect something wrong, watch out for the signs of a miscarriage and get help immediately.

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Signs Of Miscarriage At 18 Weeks

Common symptoms of a miscarriage in this week are:

  • Intense pain along with cramps.
  • Vaginal bleeding. The intensity of bleeding can vary for different women.
  • In some cases, a miscarriage may take place without any signs and can be confirmed only during an ultrasound scan. That is called a missed miscarriage.

If you are worried that it could be a miscarriage or are feeling highly uncomfortable, go to your doctor immediately.

When To Call The Doctor

If you experience the following symptoms then make sure to call the doctor right away (11):

  • Fever (100.4 degrees or higher)
  • Pelvic pain other than cramping
  • Less urination or dark colored urine
  • Severe vomiting
  • Feeling unconscious

If there are no signs of a miscarriage, schedule a regular OB/GYN visit.

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Your OB/GYN Visit

Your prenatal visit this week will include:

  • Weight check
  • Blood pressure
  • Measure the height of the fundus
  • Ultrasound scan: The second-trimester ultrasound screening, also called an anomaly scan, is done this week. A level II sonogram may be offered to have a close look at the baby’s organ developments. It also gives information about the placental appearance and position, as well as the amount of amniotic fluid surrounding the fetus.
  • Maternal serum screening (MSS test): It is a blood test done at 14 and 20 weeks +6 days. The second trimester MSS test helps in determining the risk of Down syndrome, Edward syndrome and neural tube defects like spina bifida in the fetus. It is a part of triple or quad screen test used to determine the risk of abnormalities in the fetus (12).
  • Alpha-fetoprotein test: It determines the amount of alpha-fetoprotein in the mother’s blood. It is done to assess the risk of chromosomal disorders in the fetus. (13).

If everything is normal, continue following a healthy lifestyle and diet. Next, we have a few tips to help you with that.

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[ Read: 15th Week Pregnancy ]

Tips To Follow

Here are a few tips to follow for a healthy pregnancy:

  • Follow a good lifestyle and eat home cooked food.
  • Stay hydrated.
  • Eat small meals at regular intervals. Include grains (like cereal, bread, pasta, and rice), vegetables, fruits, milk and dairy products, meat, and beans in your meal.
  • Engage in moderate physical activities like walking. This boosts your energy level.
  • Quit smoking, illicit drugs, and drinking alcohol as it can affect the growth of the fetus.
  • Maintain oral hygiene.
  • Keep stress at bay.
  • Wear loose, breathable clothes and comfortable slippers or shoes.
  • Get enough rest.
  • Do not take any medication without the doctor’s permission.
  • Do not sit with legs crossed and avoid any faulty postures as it can cause a backache.
  • Avoid fatty and oily foods to prevent heartburn.
  • Consume more fiber to reduce constipation.
  • If your work requires you to sit for a long time in one position, try to get up often and walk around a little every one hour.
  • Spend more time with family and friends.


  • Research about the best childbirth classes in your area.
  • Do not miss any of the appointments with the doctor.
  • Book appointment with a dentist for an oral checkup.
  • Start reading pregnancy books and engage in activities that keep you happy.

Your partner can support you with these things and more. Keep reading to know how he can help you.

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Tips For Dad-To-Be

Here’s what your partner can do:

  • Share the responsibilities of the household chores.
  • Create a pleasant environment at home.
  • Accompany you to all the prenatal visits.
  • Plan for maternal shopping.
  • Give you a good neck and foot massage when you need one.

At 18 weeks, you should focus on following a healthy regime and develop positivity. The joy of pregnancy is always accompanied by certain discomforts, but they are temporary. You will slowly get used to it, and all the pains will wane after the little one arrives.

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Do you have any experiences to share with us? Let us know in the comment section.

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shreeja pillai

Postgraduate in Chemistry and content writer. She has worked as a research analyst with a leading multinational pharmaceutical company and also holds a diploma in pharmaceutical regulatory affairs. Her interest in the field of medical research has developed her passion for writing research-based articles. She is a writer for MomJunction and aims at providing informative articles based on health and wellness. Apart from writing, she takes a great interest in music and traveling. know more about her at https://www.linkedin.com/in/shreeja-pillai/
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