Women who want an abortion in the early weeks of pregnancy must continue to take the pills at a clinic and not at home, unless the health secretary, Andrew Lansley, stipulates otherwise, a judge has ruled.

In many countries women take the first of two pills in a clinic and are given the second to take away, ensuring they can undergo the abortion in their own home with family or friends present. This is not the case in the UK.

The British Pregnancy Advisory Service (Bpas) has failed in a high court bid to secure a new interpretation of UK law. Its lawyers argued that wording relating to the prescription and administration in a clinic of drugs needed to bring about a medical abortion – two pills, taken 24-48 hours apart – could be defined as the prescription and issuing of the medication, allowing women to go home after the first visit.

Bpas says that the second visit can be a hardship for women living some distance away, and that some are afraid they will miscarry on their way home.

Handing down judgment, the court ruled that this interpretation of the law was not possible. But the judge effectively put the onus back with the government, ruling that the 1967 Abortion Act, as amended in 1990, enables the secretary of state to react to "changes in medical science" as it gives the health minister "the power to approve a wider range of place, including potentially the home, and the conditions on which such approval may be given relating to the particular medicine and the manner of its administration or use".

Bpas called for a change in the law. "Bpas will pursue its case to provide an early medical abortion service that is based on evidence and best international practice. Women deserve this, and we would be failing as a charity if we failed to advocate for the services women need," said its chief executive, Ann Furedi.

"It cannot be morally right to compel a woman to physically take tablets in a clinic and to subject her to the anxiety that symptoms will start on the journey back when her doctor knows it is safe and indeed preferable for her to take these at home.

"If the law as it stands cannot allow what is safe, right and proper, then it is not fit for purpose and must be changed to reflect modern medical practice. But if the law as it stands allows the secretary of state to approve a woman's home as a 'class of place' for abortion then this is what he must do. We look forward to discussing with ministers and officials how quickly this can happen."