18 Weeks Pregnant with Twins

Here’s what to expect when you are 18 weeks pregnant with twins:

Fetal Development

By 18 weeks in the twin pregnancy each of your twins averages 5.5″ (14 cm) long from head to rump and has the following measurements:

Head circumference: 6″ (152 mm)
Abdominal Circumference: 5.25″ (133 mm)
Femur Bone Length (about from the waist to knee): 1″ (25 mm)

Each baby is about the size of a bell pepper.

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What to Expect

Typical weight gain for Mom at this point is between 1 to 1.5 pounds/week (0.5 to 0.7kg).

(RELATED: Check out the Dad's Guide to Twins Youtube channel for additional helpful twin tips and tricks videos.)

Total weight gain for the twin pregnancy so far will average between 18 to 27 pounds (8.2 to 12.2kg).

Picture and Video

Here’s an ultrasound video of what you might see at 18 weeks pregnant with twins:

Belly picture at 18 weeks:
18 Weeks Pregnant with Twins Belly

What to Prepare This Week

When Mom is 18 weeks pregnant with twins, can work on your twins’ nursery and sleeping arrangements. There are several crib options for twins that will meet your individual living situation. Decide if you want them to share a crib initially or each have their own crib from the start.

I clover my twinanigans shirt

From Your Fellow Parents at 18 Weeks Pregnant with Twins

Ashton W. – “our twin preparation has been very smooth and amazing. It’s exciting to see their nursery and all the baby stuff coming together. I feel wonderful, the babies are doing fine and moving along with this beautiful journey.”

Dad’s Thoughts

By the time Mom reaches 18 weeks pregnant with twins, you are likely half way through the pregnancy. While your wife had a rough 1st trimester, things have been pretty easy for you. Get mentally ready as you’ll need to step it up in the coming weeks to support your wife and family as she becomes more physically burdened with the twin pregnancy. If you haven’t already found out, you should know the gender of your twins by 18 weeks. This knowledge brings a whole new excitement to preparations.

(RELATED: Your twins will need a lot of gear. Here's the complete twins baby registry checklist to get ready for your twins' arrival.

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Still wondering how to prepare for your twins? I cover specific things you should know and prepare for in my Dad’s Guide to Twins book. Learn more about the book here.

I clover my twinanigans shirt

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(RELATED: Still expecting twins? Will you be having two boys, two girls, or boy/girl twins? Answer these quick questions to see what several old wives’ tales claim you’ll be having….)

Sources: When You’re Expecting Twins, Triplets, or Quads: Proven Guidelines for a Healthy Multiple Pregnancy by Dr. Barbara Luke and Tamara Eberlein and Babycenter’s Average fetal length and weight chart

Further Reading

Dad's Guide to Raising Twins book
Don't forget to pick up a copy of the definitive guide to raising twins. "Dad's Guide to Raising Twins" was written for fathers of twins to help guide you through the first several years with twins. Click here to learn more about the book and get your copy.

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