Lesley Regan, the new president of the Royal College of Obstetricians and Gynaecologists, is only the second woman to hold that office and the first in 64 years. If that seems extraordinary in a profession where the clients are exclusively female – as are most new doctors – there is no doubt that Regan will soon sweep out any lingering male bias in dusty college corners.

Regan, 60, a professor of obstetrics and gynaecology at Imperial College London, is straight-talking and robust and keen to help prevent the disasters that can wreak havoc in women’s lives, from unwanted teenage pregnancy to obesity, which can end in problems in childbirth for both mother and baby, or before that, in miscarriage – her own area of research.

“If we were able to persuade the next cohort of 20-year-old girls that their pregnancies would be immeasurably safer and better if they lost weight by doing some more exercise, ate more sensibly and stopped smoking, what a contribution that would be,” she says.

She heads a battalion of people who could make a difference. “We shouldn’t underestimate how much the members and fellows of this college can do, because there’s 14,000 of us and we’re growing. About half of us are not in the UK, but across the world. That’s a lot of people looking after girls and women at regular times in their life course,” she says.

Her chosen field looks after more than half the population (51%) at some point in their lives and manages “some of the most contentious and sensitive issues in medicine, which can no longer be swept under the carpet,” she said in a barnstorming address on her accession to the presidency. “We have to persuade the government that the health and wealth of a nation is determined by the health of its girls and women.”

She is an unapologetic interventionist. Consultants in most specialities wait for people to come to them with health problems. But in her field, you have many chances to get in first. When women are pregnant, they are receptive, she says. They want the best for their baby. “I think we need to use those opportunities of meeting with them before pregnancy, during pregnancy and then after the pregnancy to talk about other factors which are going to help them live healthy lives in the future.”

She means not only talking about smoking and contraception and – very importantly – mental health, but taking the bull by the horns and warning young women that they need to lose some weight. It’s a conversation some doctors shy away from. Not Regan. “I do certainly [tell my patients]. And I sometimes get myself into trouble. Sometimes people who are very overweight get very, very defensive about it. But I do think it’s very important and I think I have a responsibility to do that.”

She had just come from explaining to one of her patients (she is also a consultant at St Mary’s hospital, London) that fat is not padding. “Fat is an organ. It produces all sorts of chemicals and it’s going to affect the quality of the way she ovulates, the way she implants her embryo – and if she can get down to a normal BMI (body mass index) or certainly down to 30, then she’s going to dramatically improve her outcomes,” she says. And if young women can get down to a normal BMI – 18.5 to 25 is considered healthy – before they get pregnant, “their deliveries are so much simpler”, she adds.

Around 15-20% of pregnant women are now very overweight or obese – getting on for one in five. Hospitals have had to invest in special beds, she says. That, together with women having babies at an older age, means there are many more complicated pregnancies than in the past.

She talks of three life stages: adolescence, the reproductive era and the years after the menopause. Women will spend roughly 12 years in the first, 35 in the second and the longest of all – 40 years or more – in the post-reproductive years as we all lead longer lives.

It is important to get in early. She wants the government to invest in girls. “Unless we’re going to improve the way teenagers learn about sex and relationships, they are going to continue to have unplanned pregnancies at a very early age. Then they drop out of secondary education and they rarely go back, and this whole cycle continues; and as we all know, the epidemiological and sociological statistics are frightening. The inequalities are always greatest in those who are poorest and most poorly educated,” she says.

She has been tremendously influenced by Sir Michael Marmot, who as a leading epidemiology professor at UCL has pioneered research on health inequalities. “Why is it we treat people, only to put them back into the place where they got ill?” she asks. Marmot said that only a third of our health outcomes are attributable to doctors and other medical staff. “Two thirds comes from all the social and epidemiological factors present where somebody is born and lives and where they are educated. It’s absolutely phenomenal.”

She believes David Cameron should have made sex education in schools statutory, so that no parent can opt their daughter out on the basis of religion. We cannot afford to go on as we are, she says, with high rates of teen pregnancies (although this is currently going down) and stillbirths – predominantly among the young – putting the UK at the bottom end of the European league.

Women should know it makes sense to plan their family, she says. “Women who space their pregnancies out by 24 months or more just have better outcomes – and those children have better outcomes. I think it’s just completely incontrovertible. It’s so persuasive.”

There is much more to do, also, to help women through the post-reproductive years of life. “I’m probably going to spend more of my life, because of the longevity of my generation, in the post-menopausal state rather than the reproductive years,” she says. “Most women like me don’t just want a long life – they want a life with good quality health.” That means advising women to do weight-bearing exercise to avoid osteoporosis and not put on the pounds, but it also means addressing taboos such as incontinence.

Regan is good at shattering taboos. It’s why she specialised in finding the causes of miscarriage when she started in medicine. And she will continue to tell it as it is.

Curriculum vitae

Age 60

Lives west London

Family Twin daughters, aged 24 Education Lady Eleanor Holles school, Hampton, Middlesex; Royal Free Hospital Medical School London

Career 1996-present: head of obstetrics and gynaecology, Imperial College at St Mary’s hospital and deputy head of surgery and cancer, Imperial College London; 1990-96: consultant and senior lecturer in obstetrics and gynaecology, St Mary’s hospital, London; 1986-90: director of medical studies, Girton College, University of Cambridge; 1986-90: senior registrar, Addenbrooke’s hospital, Cambridge; 1987-89: senior research associate, Medical Research Council; embryo and gamete research group, University of Cambridge

Public life Chair, Royal College of Obstetricians and Gynaecologists; chair, National Confidential Enquiry into Patient Outcome and Death; co-director of the UK pregnancy Baby Bio Bank; trustee, CHARM (The Charity for Research into Miscarriage)

Publications and broadcasts The books Miscarriage: What Every Woman Needs to Know and Your Pregnancy Week by Week; and a series of eight documentaries on health-related topics for BBC2 Horizon.

Interests classical music and opera, Proms season ticket holder