Twins are born during the same pregnancy, but that does not necessarily mean they have exactly the same birth time. This is why a common question among twins and their families is: Which twin is older—the one born first or the one born second?
The simple answer is that, in terms of birth order, the twin who is born first is considered the older twin.
Even if the difference is only a few minutes, the first baby delivered has an earlier recorded time of birth. The second baby is therefore the younger twin.
For example, if Twin A is born at 10:05 a.m. and Twin B arrives at 10:12 a.m., Twin A is older by seven minutes according to their recorded birth times.
However, both twins developed during the same pregnancy and are generally considered to be the same age when discussing their age in years, months and days.
This distinction becomes interesting when twins celebrate birthdays. Both have the same birthday, but their birth certificates may record different times.
Why Can There Be Several Minutes Between Twins?
Twins are not necessarily delivered at exactly the same time.
During a twin birth, one baby may be delivered first and the second may arrive minutes later. The medical team monitors both babies and may take additional steps between deliveries to ensure that the second baby is safely delivered.
In some cases, the gap can be longer depending on the circumstances of the delivery.
Does Being Born First Make One Twin Older?
Yes, by birth order.
If one twin is born first, that twin is traditionally referred to as the older twin. The difference may be only seconds or minutes, but their recorded birth times establish the order.
This does not mean that one twin is biologically “older” in any meaningful developmental sense. Both spent essentially the same period developing in the womb.
What About Twins Born on Different Days?
This is where things become even more interesting.
If one twin is born shortly before midnight and the other is born after midnight, they can technically have different calendar birthdays.
For example, if one twin is born at 11:58 p.m. on Monday and the second arrives at 12:03 a.m. on Tuesday, they have different dates of birth even though they were born only five minutes apart.
The first twin is still the older twin by birth order.
What About Identical Twins?
The same principle applies to identical twins.
Identical twins develop from one fertilised egg that later divides into two embryos. Despite their extremely close genetic relationship, they can still have different recorded birth times.
So if one is delivered first, that baby is considered the older twin.
Final Thoughts
Twins are usually the same age in everyday terms because they share the same pregnancy and birthday. However, when it comes to birth order, the twin who is born first is considered the older twin.
The difference could be just a few seconds or several minutes, but the recorded time of birth determines who came first.
So the next time twins argue about who is older, the answer is simple: check the birth certificates—the twin with the earlier birth time is the older one.
