Expectant mothers will be urged to avoid unnecessary journeys and crowds, with experts suggesting that they do not travel on trains and the London Underground at peak times.
Parents will be advised to keep babies away from crowds, while pregnant women will also be encouraged to limit the movements of their other children, so they do not bring the virus home.
The warnings come amid increasing concern that pregnant women and young children are among the groups most at risk from swine flu.
So far, more than 650 people have been taken to hospital with the virus in England, including more than 200 children. Under-fives have been three times more likely than older patients to be taken to hospital. In Scotland, 44 people have been taken to hospital, while 11 have been treated in Welsh hospitals. At least 146 cases have been recorded in Ireland.
Officially, there have been 29 British deaths involving swine flu, including four children and two mothers who died shortly after giving birth.
All except one – six-year-old Chloe Buckley, who died 10 days ago in west London — were known to have been suffering from underlying health problems.
Pregnant women are at increased risk of contracting any infection because their immunity is suppressed to ensure that their body does not reject their baby.
Experts believe that most cases of swine flu would not harm the mother or foetus, but rare cases could lead to premature labour or miscarriage or cause birth defects.
In Australia, where 11 expectant women with swine flu are in intensive care, pregnant women have been urged to stay at home when possible, and to wear face masks when they do go out.
Mask-wearing is not part of Britain’s strategy because it is thought to do little to reduce the spread of disease and encourages complacency against more useful measures, such as regular hand-washing.
The new guidance, to be published on the National Health Service website, www.nhs.uk, and circulated via parenting forums, will alert parents and pregnant women to recommendations that have been drawn up by the Royal College of Midwives and the Royal College of Obstetricians and Gynaecologists.
Senior figures from both organisations said that while significant changes in lifestyle, to avoid crowds and public transport, might not be realistic for all pregnant women and parents with babies, individuals should be made aware of the risks.
Sue Macdonald, from the Royal College of Midwives, said: “Pregnant women have got a strong instinct to protect their baby, but we have to be realistic about the kinds of adjustments people can make. If they normally have to travel on the Tube or on crowded trains in rush hour they might be better to come in later or earlier, but of course it is difficult to avoid crowds entirely. This is about being sensible and being aware of the risks."
The advice states that the simplest way to reduce the risk of contracting swine flu is regular hand-washing, especially after journeys
In separate guidance, pregnant GPs and community nurses have been told that they should not see patients with suspected swine flu.
The Government has decided against advising women to delay pregnancy until the swine flu pandemic has passed, even though such a recommendation was contained in previous plans.
The number of people off work with symptoms of flu more than doubled last week, according to figures compiled for The Sunday Telegraph. On Friday , about 177,000 people were absent with flu-like symptoms, compared with 80,000 the week before.
Aaron Ross, the chief executive of FirstCare, an absence management company that carried out the survey of 1,000 companies, said businesses should offer home working to staff who are most vulnerable to swine flu.