Twin Pregnancy Week 18: Symptoms, Baby Size, Ultrasound & more

18 Weeks Pregnant with Twins or Multiples

Medically Reviewed By
Dr. Sabiha Anjum (Gynecologist/Obstetrician)
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Reaching the 18th week of your pregnancy is pretty much a milestone for any woman. If you are pregnant with twins and are thinking that your babies are halfway through the development already and all you have to do is wait for them to grow up, then you are in for a surprise. There are numerous changes that you will experience in this week and in the coming weeks, right from your appetite to various changes taking place within your body. Certain symptoms of pregnancy can make a minor return in the 18th week and a few new ones could emerge too, catching you off-guard if you aren’t prepared for them. You are halfway through your journey and it is suggested that you prepare for the rest in the best way possible. This article will help you with some essential information every pregnant woman carrying twins or multiples should know about week 18 of pregnancy.

Video : 18 Weeks Pregnant – Symptoms, Baby Size, Dos & Don’ts

The Growth of the Babies at 18 Weeks of Twin or Multiple Pregnancy

Whether you have twins or multiples, their growth in your womb is at its usual pace, and sometimes even faster than before. One of the major signs that will assure you that your children are growing in the right sense is their movement taking place inside you. The tumbling around within the womb will be strong enough and your babies will make themselves noticed. The fluttering movements that you feel while you rest are a great sign that your little ones are getting stronger day-by-day and growing up as well.

In terms of the physical development of your twins or triplets, one of the key changes that take place is around their external surface. A lot of oil will begin to produce on their skin. This oil is termed as sebum and it is secreted in copious amounts when the sebaceous glands are stimulated. Along with it, there are numerous cells that work in replacing the previous skin that was covering your babies with a newer one. It takes care of the lush soft hair, called lanugo hair, which sheds from the body of your babies. The cells, the hair, and the oil secretion all mix together and form a substance called the vernix. It can be compared with the structure of a creamy cheese of sorts since it is white in colour and fluid in nature. This vernix surrounds the babies completely and prevents their skin from drying out. Furthermore, the temperature also needs to be regulated for your little ones and that is achieved through the presence of this covering.

Apart from this, one of the crucial roles that the vernix fulfils comes around the end of the pregnancy. When the babies are on their way out and are passing through the birth canal, they need to combat friction as well as the sudden drop in temperature once they are out. The vernix provides lubrication which is necessary for supporting the progress of the babies via the canal and it also keeps the children warm until they are wrapped up by the nurses.

What Is the Size of the Babies at 18 Weeks of Twin or Multiple Pregnancy?

A woman who is pregnant with a single child will notice that her baby will have grown substantially around this time. The length of the child, measured from the head to the butt, is around 13 centimetres, while the weight increases rapidly to approximately 150 grams. However, if you are pregnant with twins or triplets, your babies will be small and may weigh less, but not by a large degree. Most of the babies will be as large as a bell pepper.

A baby at 18 weeks is as large as a bell pepper

The expectant mother also goes through transformations in week 18 of the pregnancy. Read on to know the bodily changes, symptoms, etc.

Common Bodily Changes at 18 Weeks of Twin or Multiple Pregnancy

The changes in a woman’s body that occur around the 18th week of pregnancy are not quite different from those that have been going in the previous week or so. Most of them either reduce in intensity, while others might get stronger.

1. Increased Blood Volume and Flow

The body of the mother is under immense physical stress since it has to support all the babies in the womb as well as the body itself. Increased blood flow is a way that your body comes to terms with it, combined with an increased volume of blood production, too. Your heart might be functioning over time as a result, but your blood pressure is a tad lower than usual in such cases. This can, at times, cause you to have a head rush or a dizzy spell, suddenly making you feel lightheaded even. These occur especially if you change your orientation or stand up quickly from your seat. Lying down on one side for a quick nap can usually set things right.

2. Hormonal Changes

Hormonal changes impact various areas of your body in mysterious ways. What began as a small irritation can become repetitive this week, especially the condition of dry eyes. All the fluctuating hormones can impact the tear glands in the eyes, causing them to be less watery. You will still manage to wipe tears when you cry, but the usual dampness in your eyes will take a dip. At times, your eyesight can undergo a change as well, causing you to find your usual spectacles to not work as they used to earlier. Contact lens users also face the same dilemma. The best bet is to either use eyedrops or give your eyes a break.

3. Vaginal Discharge

The constant and increased discharge of the leaky fluid from your vagina may get irritating for you. This, too, is a result of increased blood circulation and hormonal fluctuations. It might seem strange that the same hormones, which cause your eyes to dry, are responsible for accelerating the fluid discharge in the vagina. Well, all of us might not be experts on how hormones affect each section of the body, but they sure work in mysterious ways. Nevertheless, just like the issue with eyesight, this is not a reason to worry as the discharge reduces after delivery.

A woman with swollen feet during pregnancy

Symptoms at 18 Weeks of Twin or Multiple Pregnancy

Yes, the 18th week of your pregnancy is no less than a happy time of the journey and one of the best phases of the second trimester. Even so, it is not free from pain, and you will just have to make peace with it because when you finally hold your twins or multiples in your arms, everything will be worth it.

  • Your babies will continue to grow in size in the 18th week. Their weight would increase too. Your body has no other option but to bear the increasing strain, especially on the back and the lower back region. This pain will increase over time if you do not take ample rest. Light exercises and massages will help in providing relief from this pain.
  • You will also experience swelling in your body. Swelling in pregnancy is simply due to the boost in blood circulation as well as the tendency of muscles to retain water. All these fluids end up getting pooled in different areas of the body, especially the hands and the feet. Most of the times, a little exercise and massage can reduce the swelling and it will remain nothing but an irritation, which will fade away post-delivery. If you are suffering from varicose veins, using compression socks would prove to be quite beneficial.
  • Another minor irritation that gets worse for some women during this week is the tendency to encounter nosebleeds randomly. There’s no way out of it since it is another consequence of a blood circulation boost, affecting every other area of the body.

Twin or Multiple Pregnancy – Belly at 18 Weeks

The region lying below your navel will begin to expand considerably, as your uterus increases in size with the growth of your babies. Your tummy would be as large as a big muskmelon, with those numerous babies pushing it to expand further. Touching the lower end of your tummy will help you feel your uterus easily.

Twin or Multiple Pregnancy at 18 Weeks – Ultrasound

When expecting twins or multiples, having an ultrasound scan during the 18th week of pregnancy can provide you with some more information about their growth. Primarily, if your doctor has detected your twins to be present in separate amniotic sacs, the current scan will show you something extraordinary. The constant movement of the babies can clearly depict the stretching of the twins in separate directions. Furthermore, most babies tend to yawn or even suck on their thumbs around this week. If you happen to get the scan when the babies are engrossed in these activities, you might get to see that as well.

Diet at 18 Weeks of Twin and Multiple Pregnancy

Eating healthy foods the right quantities regularly will keep you and your baby healthy throughout. You need to up your iron intake around this week. Eat lots of iron-rich foods and also drink lots of water now and throughout your pregnancy.

Foods rich in iron

Twin or Multiple Pregnancy at 18 Week – Care Tips

You don’t need to do anything out of ordinary to take care of yourself the right way. But here are a few do’s and don’ts that you need to keep in mind.


  • Get enough massages and baths to relax and be calm.
  • Try to sleep on one side so that your blood flow is not obstructed.
  • Keep yourself hydrated by drinking ample water.


  • Don’t be afraid of asking your doctor any questions regarding your baby’s health or your own health.
  • Do not overdo with exercises as it may leave you fatigued.

What You Need to Shop for at 18 Weeks of Twin or Multiple Pregnancy

Purchase a nice pillow that supports your head properly while you sleep on your side. You may want to buy an additional pillow to keep in between your legs to be able to sleep well as your pregnancy progresses. You may go shopping for yourself if you need comfortable clothes; it is a good time to buy some nice sleeping gowns. It is also a good time to start researching and shopping for your baby too.

The 18th week of pregnancy is much better and relaxed as compared to those weeks of the first trimester when nausea and morning sickness don’t leave your side. But, that doesn’t mean you exhaust yourself during this time. Take as much rest as possible, get your regular checkups, eat a healthy diet and prepare yourself mentally for the demands of the coming trimester.

Previous Week: Twin Pregnancy Week 17

Next Week: Twin Pregnancy Week 19

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