Baby Sussex — the soon-to-be-born child of Prince Harry and Meghan Markle, the Duke and Duchess of Sussex — will be seventh in line for the throne. But don’t expect this child to be anything less than a prince or princess.

Although Queen Elizabeth’s daughter, Princess Anne, opted for her children (and, therefore, grandchildren) not to bear such royal honorifics, sources told The Post that Meghan likely won’t give up the lofty title.

“All royal ranks are at the Queen’s discretion and Princess Anne set an interesting precedent by choosing to raise her children without any royal titles at all,” said Patrick Jephson, the former chief aide to Harry’s mother, Princess Diana. “[But] my guess is that Harry and Meghan’s child will already be a prince or princess by the time we see the first photo.”

According to friends of Meghan’s, who agree the baby will almost certainly be bestowed a title, the California-born actress and her husband have opted not to find out if they are having a boy or a girl.

The tot will also have dual nationality, as the first British royal to meet the criteria for US citizenship.

Meghan is reportedly planning a home birth and without the Queen’s household doctors, Alan Farthing and Guy Thorpe-Beeston, widely considered to be among the best in the business. The duchess will, however, have a helicopter on standby at the Sussexes’ new Windsor home, Frogmore Cottage, should she need to rush to a local hospital.

Since her wedding to Prince Harry in May 2018, the former “Suits” star has rewritten the royal rule book: from walking herself partway down the matrimonial aisle to not planning to pose for public photos shortly after giving birth — and even waiting to announce the baby’s arrival.

Prince William, Kate Middleton and Prince Louis
Prince William, Kate Middleton and Prince LouisGetty Images

In fact, one friend of Meghan’s told The Post that the duchess, a committed feminist, actually “felt sorry” for her sister-in-law, Kate Middleton, having to face the world’s media — while wearing a dress, heels and impeccable hair and makeup — mere hours after giving birth.

Instead, Meghan and Harry released a statement, reading in part: “Their Royal Highnesses have taken a personal decision to keep the plans around the arrival of their baby private. The Duke and Duchess look forward to sharing the exciting news with everyone once they have had an opportunity to celebrate privately as a new family.”

It’s expected they will pose for a photo call at Windsor Castle on their own schedule.

“They’re basically conducting the birth in virtual secrecy. I think it’s a bit foolish,” said Duncan Larcombe, former royal editor at The Sun. “Harry absolutely hates being the subject of speculation, and this just shows his petulance to the media . . . it’s just a shame.”

Friends said that Meghan wants to emulate the warm mothering she received from her yoga-teacher mom, Doria Ragland, who has already left her Los Angeles home to be on hand for the birth.

A friend of the family told The Post: “Meghan and Doria are like two peas in a pod. Both perfectionists, both can be controlling, but they know their own minds for sure! They just like things the way they like them. Everyone in the family says that when they’re together, Harry — who is extremely fond of Doria — will have to take a back seat. He won’t be able to get a word in edgewise.”

Meanwhile, a friend of Meghan’s estranged father, Thomas Markle, said the former “Married With Children” lighting director, who has been in ill health recently, is “devastated” at the prospect of never meeting his grandchild.

The father and daughter infamously fell out just days before the wedding when it was revealed Markle had been staging and selling ­paparazzi photos.

The friend said Thomas, who lives in the beach town of Rosarito, Mexico, “has spent the past year going over everything again and again in his head. He feels that the punishment does not fit the crime. He cannot understand why Meghan won’t talk to him. All he wants, all he dreams of, is meeting his grandchild. He is totally and utterly devastated.

meghan markle doria ragland
Meghan Markle and Doria RaglandAP

“While Doria is there, he won’t even know when the baby arrives until the rest of the world is told.”

The two were extremely close when Meghan was little, and, according to the Thomas friend, he claims he paid for his daughter’s education at Northwestern University, as well as covering her car and rent when she returned to LA after school. Things began to go downhill, the friend said, when Meghan later moved to Toronto to film “Suits.” Thomas does not like to travel and, unlike Doria, he didn’t visit his daughter.

The Thomas friend said that Meghan’s “can-do” and sometimes “controlling” attitude was instilled in her not just by Doria, but also by her father, who wanted her to feel proud of her biracial heritage.

“He wanted her to feel she could achieve anything. You have to remember, at the time that Thomas and Doria were together, inter­racial relationships weren’t so common and they faced hardships,” added the Thomas friend. “Now he really thinks that Meghan is ashamed of him.”

Baby Sussex will make history as the first royal of African-American heritage, something Meghan and Harry are hugely proud of. In 2015, Meghan wrote how, “when asked to choose my ethnicity in a questionnaire as in my seventh grade class, or these days to check ‘Other,’ I simply say: ‘Sorry, world, this is not [the TV show] ‘Lost’ and I am not one of The Others. I am enough ­exactly as I am.’ ”

Doria will have her own special bedroom at Frogmore Cottage, which received a six-month, $4 million renovation, believed to have been spearheaded by Soho House interior designer Vicky Charles, a favorite of Harry and Meghan’s friends George and Amal Clooney.

Complete with green-energy utilities, a springy “floating floor” (perfect for Doria and Meghan’s yoga) and nontoxic paint, the cottage is said to marry English and California style.

Meghan plans to return to work commitments, including patronage charities Mayhew (animal welfare) and the National Theatre, after just three months — a not-unusual amount of time for Americans but considered rather short in England. (Middleton, the Duchess of Cambridge, took six months of maternity leave after each of her children was born.)

Frogmore Cottage
Frogmore CottageGetty Images

Former Royal Editor Larcombe points out that this timing will ensure that Meghan misses a planned early June state dinner for Donald Trump.

“I’m told that there are no plans for Meghan to meet President Trump,” said Larcombe. “Not as a snub [but] — how shall we say — it’s a quite convenient period of maternity leave.”

While campaigning for Hillary Clinton, Meghan called Trump “misogynistic” and “divisive.”

It is not known if Harry will attend the dinner, although Prince William — England’s future king — is expected. Baby Sussex, it’s hoped, will mark a fresh start for the royal family amid reports of a reported fractured relationship between the brothers. The alleged rift has been attributed to everything from William having warned his sibling to take things slow with Meghan during their courtship, to rumors of William possibly having a mistress.

(A palace source said that such rumors are “false, hurtful and defamatory.” Meanwhile, another insider told The Post that “the rift is not as huge as some have made it out to be” and that the brothers sat and joked together in church on Easter Sunday, which was also the Queen’s 93rd birthday.)

As for recent reports that Meghan and Harry are being lined up for a new role that could see them moving to Africa, a highly placed royal source told The Post: “I wouldn’t be surprised if things are put on ice. It’s impossible to exaggerate how the new arrival will affect Meghan and Harry. I’m hearing nothing supporting the argument that an actual move away is in the cards.”

Finally, British bookmakers say that, if the new baby is a girl, bettors believe she’ll be named Diana.

“I’ve no doubt Princess Diana would have been extremely happy to welcome an addition to the family,” said Jephson. “She knew the transformative effect of a newborn child — not least to help heal family wounds, if there are any to be healed. And she would need no reminding that the new arrival joins an ancient family at the heart of British national identity. So amid the celebrations, all baby Sussex’s relatives will know that a lifetime of duty to crown and country lies ahead. The future of the Windsor dynasty demands it.”

Prince Harry and Meghan Markle
Prince Harry and Meghan MarkleGetty Images

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