They urged an ethics debate in parliament as it considers making such tests more widespread by obliging all health insurance companies to cover them.
The cross-party group of MPs, including some ministers and party leaders, called for a wider discussion as medical science is on the cusp of testing for a far wider range of genetic conditions.
“The advances in genetic diagnostics are forcing society to confront the question of how we want to deal with the findings it produces,” said Rudolf Henke of the Christian Democrats (CDU).
The initiative in the more than 700-seat Bundestag was joined by about 100 lawmakers from parties including the CDU, Social Democrats (SPD), pro-business FDP, far-left Die Linke and Greens.
Prenatal tests for Down Syndrome, or trisomy 21, have been available since 2012 in Germany, but most parents-to-be currently pay for them out of their own pockets.
The chairman of the German Ethics Council, Peter Dabrock, argued that parents-to-be have the right to information about the state of health of their unborn child.
The group of lawmakers, however, argued that such tests lead to more abortions of embryos considered to have defects and stigmatise people with Down Syndrome and their parents.
“People with Down Syndrome are neither more nor less happy than other people,” said the SPD's Dagmar Schmidt, arguing that they suffer not from the condition but from social exclusion.
“Parents of children with trisomy 21 should never run the risk of having to justify their baby's birth,” she said.
The initiative comes as a wider abortion debate flares again, with Pope Francis this week comparing the termination of pregnancies to hiring a “contract killer”
Meanwhile, German court on Friday upheld a March ruling confirming a ban for medical practitioners to advertise that they carry out abortions.
Gynaecologist Kristina Hänel had appealed against the controversial law after being fined for spelling out on her practice's website that she performs abortions.
The procedure is permitted in Germany but only under strictly regulated circumstances, and is usually not covered by insurance companies.
The court in its ruling suggested that lawmakers, not the judiciary, deal with the issue and told Hänel that she should consider the verdict “a special honour in the struggle for a better law”.