Barnaby Joyce has scored an early birthday present – his fifth child, a son.

After a pregnancy which made national headlines, the former deputy prime minister and his onetime media adviser, Vikki Campion, have welcomed their first baby together.

According to reports, Mr Joyce and Ms Campion’s son, Sebastian, was born on April 16 at the Armidale Public Hospital, weighing 3.8kg.

The next day, Mr Joyce celebrated turning 51.

“We are very happy and just taking it quietly,” Mr Joyce told Fairfax Media.

While Ms Campion is a first-time mother, Mr Joyce has four daughters – Julia, Caroline, Odette and Bridgette – with his estranged wife, Natalie.

The phone in his New England office was switched to message bank when The New Daily called on Friday afternoon.

Mr Joyce is said to have taken personal leave ahead of Sebastian’s birth.

The birth was celebrated by The Northern Daily Leader in Tamworth:

Reports #NewEngland MP Barnaby Joyce and partner Vikki Campion have had the baby. No word from his office yet, they're trying to get in touch with him but he's on #dadduties @The_NDL #auspol

— Breanna Chillingworth (@breannachill) April 20, 2018

Mr Joyce’s relationship with Ms Campion, 33, was publicly revealed in February, when a photograph of her, pregnant and in shorts and a T-shirt, was published on the front page of a newspaper.

The revelation that the pair were a couple and Mr Joyce had left Natalie after 24 years of marriage contributed to a tense exchange with Prime Minister Malcolm Turnbull and the then-National Party leader’s eventual resignation from his Cabinet position.

In March, Mr Joyce cast doubt on the paternity of the unborn baby, suggesting in an interview with Fairfax Media that the identity of the biological father was “a grey area”.

He said the pair had been physically apart for almost all of the time when conception could have occurred but that it made no difference because he would raise the boy as his own.

“It’s mine! On the record, there it is,” Mr Joyce said.

“And can I say, even if it wasn’t, I wouldn’t care, I’d still go through this, I’d still love him.”

Asked by Fairfax whether the arrival of the baby comprehensively removed any doubts about Mr Joyce’s paternity on the basis of date, he said “yes”.

According to The Courier Mail, it is understood the Mr Joyce told friends over a few beers a month ago he made a mistake with the “grey area” comments.

Mr Joyce was asked in February by The Sydney Morning Herald what it meant to be a father again.

“I love my daughters. I have four beautiful daughters and I love them to death,” he said.

“And now I will have a son. I don’t pick winners, I’m not gonna love one more than another, but I’m not going to love one less than another either.”

In February, the couple took a 2000km roadtrip ‘babymoon’ to a rented beachside holiday home in Wooli, NSW, and to Palm Cove, Queensland. Mr Joyce is said to be very happy with Ms Campion and has said he is “committed” to her.

After the affair was revealed and Mr Joyce resigned amid the resulting scandal, Mr Turnbull introduced a ban on ministers having sexual relations with their staff.

The updated ministerial code of conduct does not ban extra-marital affairs or having children out of wedlock.