Thread by @realBockmann

The argument that a human being starts to exist at conception is really a definition, not an argument.

It's what the word "conception" means. 🧵1/11

Conception is what happens when a sperm meets and fertilizes an egg.

That's it. 2/11

Etymologically, conception means to become pregnant; to take in and hold;

for example, the mind taking in an idea, or an egg taking in a sperm. 3/11

This makes sense, because conception = fertilization.

Apart from in vitro fertilization, conceptional age is impossible to know, but the standard estimate is 2 weeks after the first day of your last menstrual period (LMP). 4/11

my.clevelandclinic.org/health/article…

That's because ovulation happens at around week 2 in a standard 4-week menstrual cycle, and fertilization can only happen within a few days after ovulation.

Actual age: embryologic = conceptional = ovulatory = fertilizational = developmental

Actual age + 2 wks = gestational age

Gestational age (GA) is measured from LMP,

but gestation--fetal development--begins at conception and ends at live birth. 6/11

. medlineplus.gov/ency/article/0…

Conception = fertilization = "fusion of an egg and a sperm" = the start of a human being = the beginning of pregnancy. 7/11

evolve.elsevier.com/cs/product/978…

Conception = fertilization = "fusion of an egg and a sperm" = the start of a human being = zygote = the beginning of pregnancy = the beginning of a child 8/11

"Conceptus" is another name for a zygote ("fertilized egg"), embryo, or fetus.

Ironically, the disdainful, unscientific, nonmedical epithet "ZEF" (zygote-embryo-fetus) acknowledges that human life begins with fertilization, which is conception. 9/11

Conception is a scientific, medical concept, not a philosophical or religious one.

Some people think there's such a thing as "ensoulment," just as some think there's an onset of "personhood." These are philosophical arguments.

Conception is a definition.
publications.aap.org/pediatrics/art…

The beginning.

11/11