IVF over 40 years: Three major milestones that changed everything.

On July 25, the world’s first baby born through In Vitro Fertilization turned 40.

Also known as the first “test-tube baby,” Louise Brown was born in 1978 to parents Lesley and John. To celebrate that anniversary, All the Moms ran a story about a mom who struggled for years with infertility but eventually gave birth to five beautiful, healthy children, all thanks to IVF.

IVF is the process by which mature eggs are retrieved from a woman’s body and fertilized in a lab with a man’s sperm, forming an embryo. That embryo is then implanted back into the woman’s body to carry out the pregnancy, according to the Mayo Clinic.

Since IVF’s start, more than 8 million babies have been born from it as a result, a recent study reported. 

With IVF so much in the news, we wondered: How far has it come over the last four decades?

We asked Dr. William Schoolcraft, the founder and medical director of Colorado Center for Reproductive Medicine (CCRM), which specializes in IVF and other fertility science.

He pointed out three of what he believes to be are the biggest advancements the reproductive field has made regarding IVF.

1. Intracytoplasmic Sperm Injection (ICSI)

Intracytoplasmic sperm injection allows a doctor to inject a single sperm into an egg with a fine needle.

Before ICSI, “if men had very low sperm counts, typically the sperm wouldn’t penetrate the shell around the egg and fertilize the egg, and so we had to tell couples with very, very poor sperm, ‘You probably won’t fertilize your wife’s egg and you need donor sperm.'”

Why it’s a big deal: With ICSI, “We could tell any male that had any sperm at all above zero, even if he had a few dozen sperm, that because we only needed one sperm per egg, we can often fertilize the eggs with his sperm and give him a baby.”

2. Blastocyst Culture and Transfer

When an egg is retrieved from a woman’s body and subsequently fertilized, it becomes an embryo that is then cultured (or grown) in a petri dish “where every 12 to 24 hours it’s just dividing; it’s going from one cell to two and two cells to four (and so on),” Schoolcraft said.

Blastocyst culture is the process of leaving the fertilized egg in the petri dish for five days to grow, as opposed to three days. This allows the embryo to divide into about sixty cells, whereas three days allows for about four to 10 cells.

After five days, the embryologist can look at the embryos to see which have grown the fastest and best, Schoolcraft said, and implant those two.

Why it’s a big deal: In the past, a doctor might implant three or four embryos in a woman’s uterus and hope she got pregnant. Blastocyst culture allows the doctor to implant only the two best, with higher rates of success. (This also cut down on instances where a woman would have three to four kids at once because all the embryos led to pregnancy).

3. Comprehensive Chromosomal Screening at the Blastocyst Stage

Chromosomal screening at the blastocyst stage allows doctors to test the embryos prior to implantation for any chromosomal abnormalities, like having less or more than the necessary 46. Chromosomally abnormal embryos “have little potential … for forming a viable pregnancy,” Schoolcraft said in a report.

Why it’s a big deal: This advancement “pretty much eliminated multiple births altogether,” Schoolcraft said. “In addition, when people did get pregnant … they already knew (the baby) had the right chromosomes. So they weren’t going to be facing a high risk for miscarriage.”