Conjoined twins occur when identical twins have fused bodies before they are born. This condition has also been known as "Siamese twins," now considered an inappropriate, outdated term. The exact ...

New reproductive technologies have yielded a vast array of novel variations on the two conventional twin types—identical and fraternal—as well as some curious twin-like sibships. When a Canadian ...

"Irish twins" is an outdated and potentially offensive term for siblings born within 12 months of each other. Very close birth spacing can bring unique parenting challenges and health risks, so ...

Carrying a twin pregnancy is not an uncommon event. It occurs when the uterus carries two fetuses simultaneously rather than one. Having twins runs in some families and age also appears to be a ...

Although there are some rare exceptions, identical twins are almost always the same sex. Because identical twins occur when a single fertilized egg splits and forms two embryos, each embryo has the ...

New reproductive technologies have yielded a vast array of novel variations on the two conventional twin types—identical and fraternal—as well as some curious twin-like sibships. When a Canadian ...