Waving a variety of placards and banners that displayed considerably better graphic design skills than the norm, around 100 protesters urged lawmakers not to back proposals that would prevent childless women donating eggs.
They argued that the changes to the Sexual and reproductive health law were discriminatory and based more on a desire to impose traditional morality than medical science.
Several MPs stopped to speak to demonstrators, as did President Raimonds Vejonis who was attending Saeima to mark the close of the spring session.
Inside the debating chamber, medical doctor Hosams Abu Meri of the Unity political party made a powerful speech asking that a decisive vote to turn the proposals into law should be put on hold.
"We can see that a very large part of our society, very many women, are not happy with this law... it genuinely discriminates against a large portion of our society," he said.
He also pointed out research that egg donation can be used beyond fertility treatments to stimulate the production of certain hormones, which might reduce the risk of women developing certain forms of cancer.
As a result, deputies voted to put the proposals on hold until the end of June.
However, Saeima did take one notable medical decision when it appointed Anda Caksa as the new health minister.
Speaking in support of the appointment, Prime Minister Maris Kucinskis insisted his administration was not operating a revolving door policy with regard to ministers and remained committed to real reforms.