This is the second child for Aguilera, 33, who is already mom to a 6½-year-old son, Max Liron, from her previous marriage to Jordan Bratman.
The pregnancy was revealed in February, a week after Aguilera had announced her engagement to Rutler, a film producer.
The 29-year-old pop star posted an Instagram video of the painful process, People.com says, as she cried, "Ow!"
"Last time I did this I was on my own with a safety pin & cube of ice @ 13," she captioned the clip. "This time I thought it was best I left it to the pro's. Sorry mom (again)."
A VERY HAPPY BIRTHDAY
Taking a page from Beyoncé, Justin Timberlake led the crowd that packed San Jose, California's SAP Center stadium at his recent concert in singing Happy Birthday to an 8-year-old boy, Julian Delan, who is autistic, E! Online reports.
His parents shared videos of the heartwarming gesture online. In the clip, Delan is seen shouting, "This is my birthday present!"
The on/off couple — who rekindled their romance last week after splitting last month — spent the weekend in each other's company and expressing their emotions for one another.
A source told TMZ.com: "Justin and Selena spent the entire weekend together and it was filled with lots of 'I love you' talk on both ends."