BABY Actually, baby is still just a twinkle in your eye. (The due date is calculated as 40 weeks from the beginning of the last menstrual cycle.)

BABY If fertilization has successfully occurred, there’s a rapidly growing cluster of cells (official name: zygote) traveling to the uterus and implanting itself there.

BABY Though still minuscule (about the size of a peppercorn), your tadpole-like baby is developing at an astounding rate and already beginning to form all of its major organs and systems.

BABY Growing by leaps and bounds, now about as big as a sweet pea, baby has a heartbeat and is beginning to develop limbs. The umbilical cord is forming, too.

BABY Still developing at lightning speed, during this week your baby will become less like a tadpole and more like a little person (like, really little — half an inch long), with a complete skeleton made of cartilage.

BABY Pick up a bean (jelly, coffee, kidney…) and imagine it with little limbs complete with webbed fingers and toes: that’s your baby this week. It can already move around. Facial features are forming.

BABY Your baby is graduating from embryo to fetus. It may be moving around a lot already, but is only about as big as a grape, so you can’t feel it. Gender is still undetectable.

BABY Bend your thumb: from the top knuckle to the tip is about the size of your baby now. Vital organs are beginning to function; limbs are getting longer and forming joints.

BABY News flash: your baby is still growing like crazy. Details like fingernails and nipples are beginning to form. This week’s food analogy: a Brussels sprout (or a fig, if you prefer something sweet).

BABY Pick up a CD (without the case): that’s more or less what your baby weighs now. Reflexes are developing. Most of the body is formed, so from now on it’s mostly about growing (let’s face it, junior won’t stop growing for years!).