Single girls have come a long way. It used to be that a woman had to rely on the discerning eye of a suitor to notice her, fall in love and propose marriage. Then, she would have to wear him down until he became comfortable with the idea of having children. But that was then ... Nowadays, not only are men replaceable sexually (buzz, buzz), but professional women can even have the family they want without having to chase down that elusive band of gold.

In The Back-up Plan, Jennifer Lopez plays Zoe. This sexy young city dweller is an educated professional, just itching to become a mother. She has dated, but there are no viable prospects on the longterm romantic horizon. So Zoe makes her plan, books an appointment with a fertility specialist and decides to go it alone. That same day, she meets Stan (Alex O’Loughlin). He’s a handsome and grounded cheese maker who sweeps Zoe off her feet. The two begin dating, and the chemistry is magical. However, there’s one major fact about Zoe that Stan doesn’t know, and it isn’t exactly her zodiac sign. Zoe eventually comes clean, confessing to her new boyfriend that she’s preggers. Now, this new couple must navigate the regular ups and downs of romance on warp speed as they prepare for a little bundle of joy.

From the word “go,” Lopez was excited about working on The Back-up Plan.

“It was time for me to do a movie again, and I just love romantic comedies,” she explains.

The role of Zoe also gave Lopez ample opportunity to channel some of her own highs and lows from pregnancy into her portrayal. During a scene in which Stan and Zoe reconnect in the country, she encounters a huge pot of stew. Like any woman eating for two, Zoe can’t help but dive right in and treat herself to a huge serving – between two slices of bread. In another scene, her romantic advances are rebuffed when her love of chicken nuggets gets in the way. Lopez was absolutely amused by her character’s ravenous cravings.

“I love that Zoe really sort of indulged,” she says, giggling. “She really liked fast food – and beef.”

Lopez also has a lot of respect for the hard choices that her character makes in the comedy.

“I have so much respect for single moms,” she admits.

She even notes that they’re admirable for being able to juggle so much.

O’Loughlin marveled at the skill his co-star used to play her part. For him, it was a thrill to work alongside Lopez’s character.

“Jennifer’s the queen of romantic comedies,” he notes. “She’s so comfortable in the genre.”

Off-screen admiration transfers to on-screen lust between their respective characters. Lopez and O’Loughlin heat up scene after scene with sex appeal. They even managed to keep things spicy, despite set visits from Lopez’s husband.

“He was actually just behind the camera with a Taser,” jokes O’Loughlin.

Truthfully, Marc Anthony, Lopez and O’Loughlin met and established a rapport prior to shooting. The actress invited her leading man to tea at her estate on Long Island. There, they were able to discuss the work and get to know one another.

That wasn’t the only New York connection in the film. The story takes place in Manhattan and features a lot of local color. But in actuality the majority of shooting took place in Pasadena. Lopez has strong ties to Southern California: Her father lives in Pasadena, and the actress even opened a restaurant – Madre’s – in the town back in 2002.

O’Loughlin is also a bit of a local. Although he hails from Australia, the actor has had a successful career in Hollywood. After working on the cable series “The Shield,” he went on to appear on other TV shows and has even recently been cast in CBS’ retooling of “Hawaii Five-O.” Not only is he proud of The Back-up Plan, but the actor has fallen in love with his new home.

“I’m deeply grateful to work – to live and work – in this country,” he explains.

The heartthrob even used the role to build up his “body” of work, much to the delight of female moviegoers.

“I did get kind of fit for the part,” he jokes.

The Back-up Plan releases in theaters April 23.