The number of UK women dying in or around childbirth has fallen, a report has found.
But its authors said even more lives could be saved if mothers-to-be were pushier about seeing more senior doctors or midwives where they were unhappy with their care, and if more women heeded advice to have flu jabs during pregnancy.
The report, Saving Lives, Improving Mothers' Care, which was published by a coalition of academics, researchers and charity representatives and led by Oxford University's National Perinatal Epidemiology Unit, found maternal deaths dropped from 11 per 100,000 in 2006-08 down to 10 per 100,000 in 2010-12.
Among the 321 women who died from conditions caused or exacerbated by their pregnancies, nearly three quarters suffered from pre-existing conditions.
And two thirds of the deaths were a result of medical and mental health problems in pregnancy, rather than direct complications such as bleeding.
Oxford professor Marian Knight said although having a baby was becoming less and less deadly, better antenatal care and simple precautions were needed.
One in 11 of the women who died over the years covered by the report had influenza, and researchers said more than half of these deaths could have been prevented if the women had been vaccinated.
Yet only a quarter of pregnant women do get the jab, Professor Knight said.
"Indirect deaths are the biggest area where we need to see some action," she said.
"I cannot overemphasise the importance of flu vaccinations during pregnancy."
Prof Knight agreed there was a risk that some women would decide it was safer for them or their babies to stop taking certain medicines, without first consulting their doctors.
"That's quite possible, which is why if they've had those discussions before they get pregnant - even if they're not planning to get pregnant - if they have had those discussions as part of their medical care they're more likely, I would hope, not to stop taking their medicines," she said.
She urged prospective mothers, especially those with pre-existing conditions, to be persistent about getting the best care - though she acknowledged many women are at their most vulnerable when pregnant or giving birth.
"For women who've got health problems, particularly rarer health problems, they will be an expert patient. So I think it's making sure that women feel that they are able to say, 'Well, I know that Dr Jones is the expert in this - I'd like his advice'," she said.
Older women were more at risk, the report found: among women aged 20-24, there were only 6.9 deaths per 100,000 births.
For those aged 35-39 that figure more than doubled to 15.2 deaths per 100,000, and once women reached their 40s, the mortality rate jumped to 22.7 per 100,000.
Living in an underprivileged area or being born outside the UK were other risk factors.
For instance, a woman's chances of dying during or shortly after her pregnancy tripled if she was born in Nigeria, Prof Knight said.
The report prompted renewed warnings from Public Health England (PHE) that pregnant w omen are at increased risk of serious complications and death from flu compared with other healthy adults.
Mary Ramsay, head of immunisation for PHE, said these risks increased in the later stages of pregnancy.
"Getting flu during pregnancy can lead to an increased risk of miscarriage, premature birth or having a low weight baby. Having the vaccination reduces the chances of getting flu, which in turn means the risk of these complications is significantly reduced," Dr Ramsay said.
"We know that mothers want to do all they can to protect their babies and it's not too late for pregnant women to get vaccinated."
The vaccination is available free to pregnant women.
The Royal College of Midwives' director for midwifery, Louise Silverton, said: "We welcome this long-awaited report and the drop in maternal deaths due to pregnancy complications, such as eclampsia, blood loss or blood clots.
"However, we remain concerned about the high level of deaths amongst women with pre-existing medical conditions, such as a cardiac or neurological conditions.
" We need to break down communication barriers and ensure translation services are readily available for women not fluent in English. We also need more midwives and maternity support workers to deal with the increasing complexity of pregnancy and better teamwork with doctors to provide seamless maternity care ... The NHS needs to do more to prioritise these women's care in its already overstretched maternity services."