Your Twin Pregnancy: Week 18 to 20

Congratulations, you’re halfway there…well, almost. Since Week 37 is considered full term in a twin pregnancy, by Week 18 you are just about halfway through with your journey. Hurrah!

My Twin Pregnancy Week By Week

A page from the new pregnancy planner, My Twin Pregnancy Week By Week.

So what’s going on inside your body right now? Well, at Week 18, your babies are fully formed and are approximately five inches long, and weigh close to five and quarter ounces each, while at Week 20, they will measure about six inches long and weigh nearly nine ounces each. That’s a pretty significant increase in two weeks but there’s still plenty of growing to do. At this point in your twin pregnancy, you should be gaining about one pound a week. By the time the third trimester rolls around, though, that should increase to a pound and a half. Whew, that’s a lot of weight but you can do it!

At this halfway marker, you are also entering the “honeymoon” stage of your twin pregnancy—your morning sickness is finally a thing of the past, and you are still able to move around with relative ease. But that won’t last for long so try to enjoy these few fleeting weeks of mobility. Your appetite should increase now, too, which is great because it’s time to pack on those pounds if you want your babies born big and healthy. Remember to concentrate on protein—lean meats and fish—as the amino acids found in protein are essential in building cells and vital in the growth and development of fetal heart, brain, tissue, and muscle. It’s what puts the weight on both you and subsequently your babies. So eat up!

Week 18 is also the time when you should have scheduled an anatomy scan or level 2 pregnant woman getting an ultrasoundultrasound to evaluate the health of both your babies. It takes about 30 to 45 minutes and is pretty standard stuff: With the help of ultrasound technology, the technician or doctor will measure the growth of each baby’s head, femur, and abdomen, checking for abnormalities. He or she will also evaluate the four chambers of the heart, kidneys, lungs, liver, and spine. Furthermore, the technician will determine if you have the right amount of fluid in your amniotic sac(s), an important factor for moms carrying identical twins as too much or too little fluid could signal a problem such as twin-to-twin transfusion syndrome (TTTS). And finally, depending on the position of your babies in your uterus at the time of the exam, the technician may be able to determine the sex of each twin as well.

Meanwhile, during this month’s office visit, your doctor will check for anemia as moms carrying twins are more prone to the condition than moms of singletons. No worries, though, as the fix is a simple one—iron supplements. (One sour note here—iron supplements are notorious for causing constipation.) As long as you aren’t experiencing any complications, the rest of the visit should be pretty routine. You know the drill—you’ll get weighed, your belly measured, your blood pressure taken, and then you’ll be asked to pee in the cup!

Moms expecting twins finally get a payoff for all their hard work right around Week 18. For this is about the time that you’ll feel your babies moving (quickening). When the kicking action begins, it’s great fun to try to guess which body part is banging against your stomach lining, or worse, pushing hard against your cervix (ouch!). And with two babies going at it, some moms find it very uncomfortable. The best way to make them stop all the fussing about? Go for a walk. Slow, gentle movement will quickly put them to sleep.

Finally, you’ll want to register for a childbirth class around Week 20, with sessions starting no later than Week 24. Why so early, you ask, especially since women carrying singletons usually wait until their third trimester to enroll? Women expecting twins deliver early or are often put on bed rest. If you schedule your childbirth classes too late in your pregnancy, you may just miss out on all the fun so it’s better to complete the course sooner rather than later.

15 thoughts on “Your Twin Pregnancy: Week 18 to 20

  1. yasmin

    Hi I’m 18 weeks pregnant and gave started feeling movements from my twins but only feeling it on my left hand side of my belly is this normal?

    1. Christina Baglivi Tinglof Post author

      I’m not a doctor. But yes, I’ve heard of this. It’s still soooooo early. Many moms do not feel kicking for a few more weeks (some feel it this early but it’s just the beginning). But call your doctor; that’s what he or she is there for. It will definitely make you feel better once you hear it’s all ok.

  2. leka

    Hi im just finishing 18weeks ill be 19weeks tomorrow, i javent felt my babies kicking but there healthy and fine when will i feel them kicking?

    1. Krys8087

      I am now 18 weeks this is my second set of twins (children 4&5). I felt my first set around four months and these about 15wks much sooner i knew what to look for when feeling for movement. Now they kick quite hard and move very often. Dont worry if you cant feel them yet soon enough you wont beable to NOT feel them lol. My tummy is very big right now and at 8wks the are measuring to weigh about 8 oz a piece what they would weigh around 20 wks! Everyone is different . Congrats on your little ones!!!!

  3. Tay

    I’m 20 weeks pregnant with twin girls.I’ve been having Braxton Hicks contractions,low back pain and out of breath everyday.Is this normal?

    1. Christina Baglivi Tinglof Post author

      I’m not a doctor so I would suggest a quick call to him/her to confirm what’s going on. That said, I was terribly out of breath starting around the same time. I was always huffing and puffing whenever I walked anywhere. I also had constant BH contractions, and back pain due to the extra weight. My twins were induced at 39 weeks but that was me. Call your doctor! That’s what she or he is there for!

  4. Dlisamcfarlane

    I’m pregnant with twins (18 weeks) one bigger than the other but they say the smaller one is dead is that possible? And its still inside me

  5. Tina

    First of all Congratulations to you all, Half way yay, well almost but close enough ;)
    I’m 18 weeks today with Twins also a Mother of two beautiful girls.
    I’ve felt movements here and there since 12 weeks, but not enough to tell if they were kicking or not, but i knew it was them because of my other pregnancies that i had in the past. My twins seem to take turns but most of my pressure is coming from the Right which is Twin B pressing against my side a lot and Twin A seem to have more movement all around but can only be felt now and then, Twin B is 3 days older then Twin A. i think that can have a lot to do with the development between either Twin, so the older one will be more likely to be the dominated one when it comes down to those ninja kicks and what not lol Anyways best to stay Calm and Relax and try not to stress to much, as they say if you haven’t felt them yet it will come and properly none stop. but if you really feel the concerns of your twins go and call the doctor, that’s why they there to assist you and your concerns, not long now and by 20 weeks most mother will get there other Scan hopefully that answer all the questions you may had/have. :) Enjoy your Twin pregnancy :)


  6. Morgan Eddy

    Im 18 wka prego w/ twin girla and i myself am an full-identical twin. How’s that possible even?
    **plus,my tech says thet yahe seperate sacs. Same day birth and their placenta is fussing together….wtheck

    1. Christina Baglivi Tinglof Post author

      Speak with your doctor but I would concentrate heavily on protein as that’s what puts weight on your babies. Ask your doctor if you could start snacking on protein shakes, for instance.

  7. Bre S

    I’m about 18wks or so I’ve been feeling & seeing the movements plus seeing at least 1 heartbeat for 2 months, I have been taking prenatal vitamins (the gummies & they are super yummy lol) I just recently applied for AHCCCS as I’ve yet to been able to prove I’m pregnant (let alone if it is twins) I can’t pass a urine test (guess I didn’t study hard enough😂) I have my period into the 2nd trimester, I did with my 1st child 10yrs ago as well (I’m only now finding out about double uterus’)


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