Police officers had to resuscitate the infant. (Getty Images)

Two New Jersey police officers helped revive a newborn moments after he was born on a front lawn in Barnegat to a woman who said she didn't realize she was pregnant.

According to the Barnegat Police Department, two officers arrived just after 21-year-old Elizabeth Whitehead gave birth to her son in the yard. The officers found the baby boy unresponsive and without a pulse and immediately began CPR before the ambulance had arrived. In the ambulance the medical staff were able to stabilize the baby's heart rhythm and normalize his breathing.

The infant was stabilized and then admitted to the Jersey Shore Medical Center for further treatment Tuesday. Whitehead was treated and released from the Southern Ocean Medical Center.

According to the Lacey Patch, Whitehead also has a 9-month-old son and had no clue she was pregnant. Instead she thought early labor pains were menstrual cramps. When the pain became worse she headed to the hospital, but only made it to her front lawn.

According to Dr. Lori Gawron, obstetrician and gynecologist at the Northwestern University Feinberg School of Medicine in Chicago, some women mistakenly believe they cannot become pregnant within weeks of giving birth.

"Moms don't think how quickly after they deliver they can resume ovulation," said Gawron, who did not treat Whitehead. "They can start ovulation 25 days after having a baby."

Another complication for new moms is breastfeeding. Although breastfeeding can severely decrease the chance of a woman becoming pregnant, some women can spontaneously ovulate, especially if they are not exclusively breastfeeding.

Dr. Karen Ashby, associate professor of reproductive medicine at University Hospitals Case Medical Center in Cleveland, said she has had patients arrive at her office pregnant only six weeks after giving birth.

"If they're not getting their period they think they can't get pregnant, which isn't true," said Ashby, who did not treat Whitehead.