First Trimester

Nonidentical twins like these (also known as dizygotic twins) are the most common. Each baby grows from a separate fertilized egg (zygote). By 3 weeks each zygote has developed into a ball of several hundred cells, called a blastocyst, and is burrowing into the uterine lining.

• Implantation
• 4 weeks
• 8 weeks
• 12 weeks

3 Weeks

Twins at 4 Weeks

4 Weeks

Twins at 8 Weeks

8 Weeks

Twins at 12 Weeks

12 Weeks

Twins at 16 Weeks

 

 

 

 

 

 

Second Trimester

Your babies have their own unique fingerprints. They can grimace and squint and have started peeing out the amniotic fluid they've been swallowing. You can see their sex organs during an ultrasound.

• 16 weeks
• 20 weeks
• 24 weeks

 

 

 

 

16 Weeks

Twins at 20 Weeks

 

 

 

 

  

20 Weeks

Twins at 24 Weeks

 

24 Weeks

Twins at 28 Weeks

Third Trimester

Your babies can open their eyelids, which now sport eyelashes. Fat layers are building up under their skin, smoothing it out. They can suck their fingers and you may feel them hiccupping.

• 28 weeks
• 32 weeks
• 36 weeks

28 Weeks

Twins at 32 Weeks

32 Weeks

Twins at 36 Weeks

36 Weeks