The Unexpected Benefits of Pregnancy

Many women feel healthier than ever when they are expecting – and research is under way to find out why, reports Christine Doyle

One of the body's best held secrets is why during pregnancy many women find that the symptoms of a wide range of diseases decline substantially, only to strike back with renewed force after their babies have been delivered.

The mysterious health benefits of pregnancy

At one end of the spectrum, pregnancy can provide a glowing "moisturiser" for dry skin or a stimulant that causes thin hair to take on glossy volume. At the other end, pregnancy results in a welcome break from psoriasis or the distressing symptoms of Crohn's disease or ulcerative colitis. It can even bring relief from asthma, says Patrick O'Brien, consultant obstetrician at University College London Hospitals (UCLH).

"About one third of women get better, one third stay the same, and, inexplicably, the symptoms of another third are worse."

Some women with multiple sclerosis experience a decline in symptoms during the last three months of pregnancy, followed by a flare-up during the three months after birth. Working mothers sometimes say that, for all their tiredness, pregnancy is the calmest and healthiest time of their lives.

One of the most intriguing mysteries is why the symptoms of rheumatoid arthritis, a painful inflammatory disease in which the body attacks its own tissue, frequently go into remission. The latest research suggests that the body's protection of the developing foetus against rejection could play a large part in guarding the mother against the auto-immune disease.

Lisa Fachler, who has two sons, Alexander, four, and three-year-old Moshe, has suffered severe, at times almost crippling, rheumatoid arthritis since she was 14. Now 31, she says: "I have taken a frightening number of toxic drugs, including an anti-cancer drug – I sometimes felt I was poisoning myself."

Before becoming pregnant, she was advised slowly to come off some of her drugs, but to continue to take prednisolone, a steroid. "I was told this would not harm the baby," she says. "We had just moved to London from South Africa and the stress had made my condition much worse. The disease used to 'jump' from one joint to another.

Remission: Lisa Fachler with her two sons

"Before pregnancy, I could walk for only five or 10 minutes at a time. But by the fourth month of the pregnancy, I felt much better. I could walk and shop for more than an hour. It was my exhausted friend who had to sit down."

The improvement in her health lasted while she breastfed and fell pregnant for the second time, not long after Alex's birth. Sadly, the symptoms have now returned.

Changes in the body, both beneficial and harmful – breast cancer, it is thought, can be triggered, or its growth accelerated, while pregnant – are usually attributed to the female sex hormones, oestrogen and progesterone. Higher levels of both maintain the pregnancy and help to prevent rejection of the foetus, which contains "foreign cells" derived from the father.

However, the surge in hormones is only one essential part of a more complex network of biochemical interactions in the body during pregnancy.

Two recent studies, funded by the Arthritis Research Campaign (ARC), offer clues to a better understanding of the hormonal and immunological changes. This research, allied to immunological studies elsewhere, could lead to an era of more effective treatments for rheumatoid arthritis and, ultimately, for conditions such as multiple sclerosis, infertility, early miscarriage and perhaps skin diseases and asthma.

The two new studies have made a crucial difference, says Alex Ehrenstein, consultant rheumatologist at UCLH.

"We now know from research that patients with rheumatoid arthritis have fewer immune cells called regulatory T cells."

In a separate investigation at Cambridge University, Alex Betz and colleagues found that during pregnancy the special T cells expand substantially to prevent rejection of the foetus.

"The increase in regulatory T cells appears to be driven by the rise in sex hormone levels in pregnancy, and in effect suppresses the body's immune response to foetal tissue. In damping down the immune system, the T cells also ease the rheumatoid symptoms."

Dr Betz and his team are now planning a more detailed study of how the regulatory T cells work. In the meantime, women with rheumatoid arthritis who are pregnant or planning to become pregnant soon are invited to take part in a pilot study led by Dr Ehrenstein.

"We will take blood samples from them during and after pregnancy, and before where possible, in order to study the number of regulatory T cells and how well they are working," he says. "Once we know exactly what is happening, the hope is to design therapies to target the defective cells and restore their function."

It might also be possible, says the ARC, to offer hormone treatment to women with rheumatoid arthritis to counter the symptoms, particularly after they have given birth.

Medical advances cannot come soon enough for Lisa Fachler. "I am afraid for the future: I am still a young woman with two small children. It is so frustrating to feel so well during pregnancy, only to relapse later."