The Hormone Cliff: What Happens When the Placenta Leaves

Week 40 · Prenatal

You've been growing this baby for nine months. And for nine months, your placenta has been running the show.

It has been your body's hormone factory — pumping out estrogen, progesterone, and a hormone called hPL (human placental lactogen) that kept your baby nourished and growing. These hormones shaped how you felt, how your body worked, and how your blood sugar behaved.

And then, within hours of delivery, the placenta leaves. And those hormones fall off a cliff.

Understanding this one thing — what doctors sometimes call the hormone cliff — will help you make sense of almost everything that happens in the first week after your baby is born.

WHAT THE CLIFF ACTUALLY LOOKS LIKE

In the 24 hours after you give birth, your estrogen and progesterone levels drop by about 1,000 times. That is not a typo. One thousand times.

This is one of the fastest hormonal shifts the human body ever experiences. It's faster than puberty. It's faster than menopause. It happens almost overnight.

Your body has to adjust — fast. And it does. But the adjustment is not always smooth or comfortable.

WHAT YOU MIGHT FEEL

In the first few days after delivery, many moms feel a wave of emotion they didn't expect. Crying without knowing why. Feeling weirdly empty or flat even when they're also deeply in love with their baby. Shaking. Sweating. Feeling too warm, then too cold. Milk starting to come in.

All of this is the hormone cliff. It's not weakness. It's biology.

The steep drop in progesterone is what triggers what's called the "baby blues" — the weepiness and emotional swings that peak around Day 3 to 5. We'll talk more about that soon. For now, just know: it's normal. It's temporary. It's chemistry, not a sign that something is wrong with you or your love for your baby.

WHAT THIS MEANS FOR YOUR BLOOD SUGAR

Here's the good news that almost no one tells GD moms: when the placenta leaves, so does hPL — the hormone that was blocking your insulin all this time.

That blockage disappears almost immediately. For most moms with gestational diabetes, blood sugar begins to normalize within 24 to 48 hours of delivery.

You may no longer need insulin or medication. You may find that foods that spiked your glucose during pregnancy no longer affect you the same way. This is real. This is biology. Your body is reclaiming its ability to regulate blood sugar.

But — and this is important — normalized blood sugar is not the same as no risk. The 70% statistic we've talked about hasn't changed. GD was a signal about your metabolic health, and that signal still matters.

We'll keep walking this road with you, postpartum. You don't have to figure any of it out alone.

WHAT TO EXPECT IN THE FIRST 72 HOURS

Hours 1–24: Placental hormones dropping fast. Blood sugar normalizing. Energy crashing. Adrenaline from birth may keep you awake even when you're exhausted.

Days 2–4: Progesterone withdrawal in full effect. Milk coming in. Baby blues may peak. You may cry and not know why. This is normal.

Days 4–7: Things begin to stabilize. A new hormonal rhythm — centered around prolactin (the nursing hormone) and oxytocin (the bonding hormone) — starts to emerge.

Your body is not broken. It is rebuilding. Give it grace.