We just finished dinner and a tub of

vanilla ice cream is opened up in the room

next door, it’s about 500 feet away.

I have no idea this is happening.

My wife on the other hand is completely

overwhelmed by the smell of vanilla.

In her words it’s assaulting her senses

and I also notice, she hasn't touched her champagne.

When she bolts to ladies room after feeling

nauseous on the dance floor,

it hits me we're going to have a baby.

We had a beautiful baby girl

a few months later.

but ever since the wedding I wanted to

find out more about why pregnant women

get this super human sense of smell.

And what causes those 2 a.m. pickle cravings?

How does mom's diet influence

the baby's favorite foods?

On this Mother's Day addition of Reactions,

we’ll explain these and other amazing

science facts about pregnancy.

Well like many things in pregnancy,

the changes that a woman's, um, that

occurred to a woman senses really

are largely related to hormones.

During pregnancy are levels of estrogen

increase quite a bit and as levels of

estrogen change we may note different

aspects of our senses and certainly

smell and taste are, are big ones.

Probably two-thirds of pregnant women will

report that they're very sensitive to odors.

But when it comes to the science that

tries to investigate this, there's

not a lot about evidence for it.

What may be changing as that what's the lowest

concentration of an odor can detect from

maybe the change in how much you like the odor.

That, what was once pleasant now is unpleasant.

There are a lot of hypotheses.

Unfortunately, that's mostly what they are,

about how these cravings occur.

Leptin is secreted by our fat cells.

Leptin is known to decrease our appetite

and increase your metabolism.

We know that that leptin changes during pregnancy.

Neuropeptide Y is another substance

that's out there that's considered an

appetite stimulant and has been shown

to rise as pregnancy continues.

There is evidence that there may be

heightened bitter sense taste sensitivity,

especially during the first trimester.

There's a whole host of hypothesis is

why that maybe the case, and actually

that this heightened sensitivity

may be protecting the fetus.

Because it's - one of the results,

is mothers are eating bitter tasting foods

that could contain toxins.

Just like they're learning about your voice,

about the language you speak, they're also

learning about the foods that you eat.

It's a really beautiful and elegant system

that is common to all mammals, is that

the first way in which we learn about

foods are through these flavors

they get transmitted from the diet

via the bloodstream into the amniotic

fluid and then mothers milk.

The baby has a well-developed sensory

system that can detect these flavors.

The baby we'll be learning and there

is research showing that if you eat

these foods, your baby is at an

advantage when you first offer

those foods and will like them.

The whole like neural and hormonal

interactions for mother baby or

parent baby are really quite powerful.

We know that oxytocin is a chemical messenger,

it's released in the brain and it's released

in response to a social contact,

particularly skin-to-skin contact.

What it then does insights desire for further contact.

So it’s part of the reason that

we place a baby immediately on

mommy's belly or up near her chest,

we want that skin-to-skin contact to begin.

High estrogen in pregnancy causes

an increased throughout

the pregnancy of the number of

oxytocin receptors in mommy's brain.

And then as oxytocin starts to surge

in labor, so baby and mom here then

exposed to that oxytocin and it's

literally would be like trying to set

them up to start craving each other.

In some ways if you think too much

about how all of these things work,

very important for your doctor

to be thinking about it,

but as the person who is going through it,

sometimes it's to try to recognize these

are changes that happen, they’re natural,

they’re important.

They probably have a role,

they're doing something good,

but not to the point where we

would become so obsessed that

we miss the miracle here,

because really indeed,

it certainly is.