Approximately 40 percent of pregnant women complain of thinning hair or hair loss over the course of their pregnancies, and in the 2 to 3 months that follow delivery. Here's the good news: It's usually temporary and your hair will grow back!

While some pregnant women may actually see an improvement in the thickness and shininess of their hair due to an increase in estrogen and as a side effect of prenatal vitamins, there are many reasons others experience the opposite.

First, hormonal changes cause a sudden shift in the levels of estrogen and progesterone your body is producing during pregnancy and for a period of time after delivery. A surge in progesterone can have a drying effect on your hair causing it to become brittle and break easier. So it's important you keep your hair moisturized throughout your pregnancy.

The function of your thyroid gland can also change after pregnancy, and low levels of thyroid hormones can lead to hair loss. Have your doctor check your thyroid  hormone levels after you deliver because this issue can be easily fixed with certain medications. 

Mineral deficiencies can also wreak havoc on your hair. A physiological anemia occurs during pregnancy that can leave many women iron deficient, potentially leading to hair loss. So make sure you stay on an iron supplement even after your pregnancy to help balance out your levels. Many women often lack sufficient amounts of magnesium and zinc as well. Your levels of these vitamins can easily be checked by your doctor and supplemented, if necessary.

Vitamin deficiencies can also contribute to your thinning locks. Many new moms find they are low on vitamin B complex after childbirth. This can again be supplemented, but eating a balanced diet rich in natural oils, complex carbohydrates and protein can help. These nutrients are essential for maintaining good cellular growth, which can lead to healthier hair follicles.

There are certain foods -- which I call hair-growth superfoods (though they certainly have not worked on me!) --  that can improve the health of your hair. Those include sweet potatoes, which are chock full of nourishing caroteins; French beans, which count vitamins A and B among their nutritional arsenal; as well as garlic and tomatoes.

If hair loss is a problem that seems to be sticking around, you should check in with your dermatologist since there may be other factors which need to be more carefully considered.

The post Hair loss in pregnancy: It's only temporary! appeared first on Ask Dr Manny.

Dr. Manny Alvarez serves as Fox News Channel's senior managing health editor. He also serves as chairman of the department of obstetrics/gynecology and reproductive science at Hackensack University Medical Center in New Jersey. Click here for more information on Dr. Manny's work with Hackensack University Medical Center. Visit AskDrManny.com for more.