Oklahoma authorities have charged a couple with multiple sex offences involving their two-year-old daughter and their unborn child.

Gerrad Coddington, 25, and Christina Nelson-Coddington, 29, both of Pauls Valley, have been charged with first-degree rape, incest, child abuse and conspiracy.

They were previously charged in June with manufacturing child pornography, lewd acts with a minor and violating the Oklahoma Computer Crimes Act, according to Attorney General Mike Hunter.

But new information uncovered during the investigation allege that the couple beat, handcuffed and raped their two-year-old daughter.

Oklahoma authorities have charged Gerrad (pictured), 25, and Christina Coddington (both pictured), 29, with multiple sex charges, including rape and incest, involving their two-year-old daughter and their unborn child

Authorities allege that other victims in the couple's care were also beaten, handcuffed and raped.

According to the information filed on Wednesday, evidence was also uncovered that Gerrad had conspired to commit incest with his unborn child.

The US Attorney's Office is pursuing charges against the couple for production of child pornography, which carries a lengthier sentence than state charges for the same crime.

In Oklahoma, the maximum penalty for manufacturing or distributing child pornography is 20 years in prison, but federal law carries a mandatory sentence of 15-to-30 years.

The Attorney General's Office launched an investigation into the couple after the National Center for Missing and Exploited Children provided the office a tip.

That tip contained information that the Coddington's allegedly shared a pornographic image of a minor on a social media website.

Authorities are alleging that the couple beat, handcuffed and raped their two-year-old daughter. Investigators said there was also new evidence uncovered that revealed Gerrad had conspired to commit incest with his unborn child. Pictured is Christina Nelson-Coddington, 29

Authorities investigating were able to develop probable cause to arrest the suspects within three days of receiving the tip.

'Children are among the most vulnerable and defenseless in our society and crimes against them will never be tolerated by my office,' Attorney Hunter said.

'We will also ensure those who commit these types of crimes are held accountable and punished to the full extent of the law.

'I appreciate US Attorney Downing for partnering with us on this case to ensure justice is served and those who committed these horrific acts are unable to do it again.'

They are being held on $5million bonds each.