Mohammed Jubayed came into the world shortly after midday in a baking hot military tent in the chaos of a vast refugee camp in Bangladesh, now home to nearly a million Rohingya.

Just an hour earlier, a cycle rickshaw had pulled up carrying his young mother Hasina Aktar clutching her stomach and moaning in pain in the throes of labour with her second child.

The United Nations says pregnant or breastfeeding women account for one in 10 of the estimated 520,000 Rohingya who have arrived in Bangladesh over the last six weeks after fleeing an upsurge in violence in neighbouring Myanmar.

Victims of one of the worst humanitarian crises of the 21st century, these women and their newborn babies are even more vulnerable than most to the desperate conditions in the camps, where even getting food and clean water is a battle.

Many expectant mothers have walked for days to reach safety in Bangladesh, often without adequate food or water.

Aid workers say some are bleeding to death in the camps, where most endure child birth without medical help.

Two older women help Hasina, 20, walk the few steps from the rickshaw to the tent, a makeshift delivery clinic that has just been put up by Bangladeshi soldiers in Kutupalong, the largest of the camps on the border with Myanmar.

Inside, the heat is almost unbearable. Hasina lies on a single mattress on a lino floor, her hands gripping the side of the tent as she writhes in pain, small beads of sweat gathering on her skin.

One nurse holds her down by the feet when the pain becomes too much; another fans her with sheets of paper.

Hasina's mother-in-law Fatima, who is 40 but looks much older, is the only relative present. She crouches by Hasina's side and strokes her hair to try to calm her.

Later, the cries of a newborn baby boy are heard from behind the blue tarpaulin divider that offer a bare minimum of privacy.

'IT'S NOT EASY'

Mohammed's birth was not easy, but his mother is still one of the luckier ones.

Many Rohingya women give birth in their own makeshift shelters, with no formal help and no pain relief.

"We have seen some deaths, some women can lose a lot of blood," said nursing assistant Piew Das, who like all in the small team of medical workers is employed by a Bangladeshi aid organisation.

There are no special baby scales in the improvised clinic, so the doctor climbs onto regular ones, first with the baby and then without. The difference is just two kilos (less than five pounds).

According to the UN refugee agency, nearly one in five of the new arrivals is severely malnourished -- a problem all the more worrying among pregnant women.

The Rohingya, a stateless Muslim minority, have suffered decades of persecution in mainly Buddhist Myanmar, which regards them as illegal immigrants.

An attack on their village forced Fatima and her family to flee into Bangladesh four months ago, shortly before a major upsurge in violence drove more than half a million people across the border.

Still weak from the birth, Hasina will be allowed to spend the night in the military tent.

But the next day she and her new son have to return to their shelter in the overpopulated camp.

Fatima tries not to worry about how Hasina, who already has a three-year-old daughter, will look after a newborn baby in these conditions.

"What could be more wonderful than a birth?" she says.

"It's not easy, but we are getting a bit of humanitarian aid. We should be able to survive."