Ever since you found out you were expecting, you’ve become a regular shopaholic: baby clothes, a crib, bouncer, stroller…you name it. And as your baby bump begins to expand, it won’t be long before you’ll need to add maternity clothes to your shopping list.

But before you get too caught up in a shopping frenzy—what should I buy and when?—it helps to figure out which maternity items are essential and how to enhance your existing wardrobe without breaking the bank.

When and What to Buy

What’s the easiest way to figure out when you’ll need to invest in some maternity clothing? Laura Solin-Valdina of NYCSTYLIST (www.nycstylist.com), which provides maternity and postpartum concierge styling services, offers some straightforward advice: “Once you’ve outgrown your largest safety pin as an extender for the waistband of your (normally) most comfortable jeans, it’s time to start considering buying maternity clothing, especially pants and skirts,” she says.

Because each woman’s body changes differently with each pregnancy, personal stylist Maria del Puy (www.mdpfashionadvisor.com) notes how wearing maternity clothing may vary. “Some women can use regular clothing up to their seventh month with few acquisitions, while others need to go before the end of their first trimester,” she explains. Once women experience what she describes as ‘Maternity Style Fever’ (when they can no longer use their real clothes), she recommends starting with some basic pieces.

For starters, moms-to-be can build their maternity wardrobe using key pieces like pants with elastic bands on the sides, leggings and dress pants with elastic waists or sides. A basic wrap dress works well for both daytime and a night out. With regard to tops, Solin-Valdina recommends ones that are generously sized, yet still stylish. “Blousant tops and empire waist dresses cut on the bias will provide room for growth and also drape your baby bump in a comfortable and complementary way,” she explains.

In Store vs. Online; The Beauty of Borrowing

Thanks to a myriad of maternity clothing options, you’ll have plenty of choices to consider both in person and when perusing the Web. As to whether you should buy online or at a store, there are advantages to both. For basics, del Puy recommends shopping online, but when it comes to pants and dresses, stick with the in-store experience. “Go to a boutique where they can assist you with sizing, especially at the beginning,” she says. “Once you know which styles and sizes fit well, online is very convenient and easy.”

Buying off the Internet becomes even more appealing as your pregnancy develops and you’re less interested in schlepping to the post office. “Take advantage of the free shipping and return that just about every retailer offers,” says Solin-Valdina. “I recommend buying multiple colors, styles and sizes to increase your success rate and to minimize back and forth shipping returns.”

And since you won’t be wearing maternity clothes forever, experts agree that you look to other sources for everyday essentials. Repurposing select pieces in your closet just requires a mental readjustment. “Rethink the voluminous tops and dresses that you previously wore belted,” offers Solin-Valdina. “They can be worn loose in warmer climates and with an open, but shapely jacket or cardigan in cooler locales.” And don’t forget about your partner’s clothing, which can look just as fashionable on an expectant mom. “Take advantage of the influence that menswear has on women’s clothing today…you have your partner’s closet to raid as well,” she adds.

Posh and Practical Postpartum

Once your baby is born, you’ll understandably be eager to get back into your pre-pregnancy clothes. But don’t rush it; experts advise sticking with side elastic paneled pants and tunics with leggings for maximum comfort. If you’ll be nursing, consider tops and/or dresses that are either V-necked or that unbutton at the top. Solin-Valdina wore these types of tops when nursing her two sons and continues to recommend similar styles for her clients. “It’s more comfortable than lifting up your shirt to nurse,” she explains.

Speaking of breastfeeding, don’t forget to invest in a few nursing bras. Del Puy suggests a generously sized bra in a natural material like cotton, while Solin-Valdina recommends buying two or three that provide easy access.