Science: Implantation

Implantation starts at the end of the first week after fertilization, and is complete at about two weeks.1 Some argue that this is where life begins. But implantation simply marks a change of location (from fallopian tube to uterus), rather than a change of nature. The human being prior to implantation is the same as the human being after implantation (just like before and after birth—another event marking a location change).

Pregnancy Test

Admittedly, most pregnancy tests will only read positive after implantation; as a result, abortion advocates tend to argue that women only become pregnant after implantation. In fact, they’ve even redefined the word “conception” to mean implantation, arguing that’s when pregnancy begins. But the fact that a pregnancy test doesn’t come back positive pre-implantation doesn’t mean life isn’t there—it just means the test’s ability to detect that life isn’t there.2

Take, for example, the commonly used hCG pregnancy test, one which looks for Human Chorionic Gonadotropin in a woman’s urine. hCG is a hormone that is secreted by the developing placenta, and this occurs at implantation.

The release of hCG indicates the presence of the pre-born child, but it doesn’t mean she didn’t exist prior to that. We know this intuitively, of course: Just imagine you enter your home and find a stray puppy hiding in your bedroom—but you only discover it after you’ve been home for 30 minutes. Clearly, the puppy did not enter your house when you first discovered it, but instead when it managed to crawl in.

Likewise, one’s offspring first exists at fertilization even if we don’t discover her existence until implantation.

Back to The Science of When Life Begins

  1. “Prenatal Form and Function–The Making of an Earth Suit, Unit 1: The First Week,” viewed online at on May 8, 2010.
  2. It’s worth noting that pregnancy can be detected by looking for Early Pregnancy Factor in the woman’s blood, which can confirm pregnancy 24 to 48 hours after fertilization; although the test is not widely available. Viewed online at on May 8, 2010.