Credit: Workman Publishing

"What To Expect When You're Expecting," now in its fourth edition, has long been lauded as the guide to helping expectant mothers and their families navigate the uncertainties of pregnancy.

But which unexpected changes have surprised moms-to-be the most?

Heidi Murkoff, author of the best-selling book, "What To Expect When You're Expecting," revealed the top five things she said pregnant women don't expect to experience. Read her thoughts below.

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1. Changes to Your Skin

Red palms? Acne? Back-ne? Blotches, bumps, rashes? The skin you're in during pregnancy isn't likely the skin you expected. Few women get "the glow." Most get a collection of complexion problems, the likes they haven't seen since middle school yearbook photos.

2. An Emotional Roller Coaster Ride

Even if you planned pregnancy, you're likely to be surprised by mixed feelings once the pee stick confirms conception.  From excitement and exhilaration to trepidation and nagging self-doubts, it's often a wild ride of emotions. Just be sure to check in promptly with the doctor if you have any signs of depression.

3. Pregnancy Brain

The only part of your ever-swelling body that shrinks during pregnancy is your brain. Yes, your brain on pregnancy hormones is actually about 8 percent smaller, which explains why you forgot to show up for an important appointment, forgot where you left your car keys, forgot where you left your car.

Happily, so-called "placenta brain" is temporary. Your brain will plump back up nicely after delivery, at which point you'll have a new excuse for forgetfulness: sleep deprivation.

4. A Stuffy Nose

Thought baby-making hormones were all about making a baby? Actually, some pretty random parts of your body feel the affects of those hormonal surges, including your nose.

Swelling of mucus membranes means your nasal passages get clogged and can stay clogged. The result may be a constantly congested nose that may also bleed more often, snoring and a predisposition to sinus infections (which, like any infection, should be treated promptly during pregnancy).

5. A Partner Who Acts Pregnant

Maybe you've heard of "sympathetic pregnancy" in an expectant father, but you're wondering whether that's just an excuse for your hubby to raid your Chunky Monkey stash - and why he's becoming a chunky monkey himself.

In fact, pregnant women aren't the only ones with fluctuating hormone levels. Expectant fathers throughout the animal kingdom experience a surge in estrogen and a drop in testosterone - nature's way, most likely to bringing out the nurturer in the male of the species.

In "Couvade syndrome," expectant fathers can experience just about every pregnancy symptom in the book, from morning sickness to weight gain to mood swings. Yes, as a loving partner he wants to feel your pain but in fact, he may be feeling more than you give him credit for.

Find more tips and advice from Heidi Murkoff's "What To Expect When You're Expecting" book on her website HERE, and on the What To Expect Foundation website HERE.