The World Cup hosted by Russian Federation could mean "there will be young women who meet someone and then give birth".
She said women who had babies with foreigners around the time of the 1980 Olympics in Moscow often "suffered" as single mothers.
Russia's birth rate hit its lowest level in a decade past year despite government efforts to encourage Russians to reverse the demographic trend.
Some people have agreed with Ms Pletnyova that "we should bear our own Russian children". "I'm not a nationalist, but still", said Pletnyova.
Pletnyova concedes that if Russian women simply can't control themselves, they should at least have sex with visitors of the same race.
Thousands of soccer fans from 31 countries are traveling to the World Cup in Russian Federation that kicks off on Thursday with an opening ceremony in the capital followed by a match between the host team and Saudi Arabia. Forecast for the opening match gave hosts as much as 67% chance of winning the tie while Saudi Arabia is given 11% chance of winning with 22% of the game ending in a score or goalless draw.
Perhaps she was anxious that the women would face a future of single parenthood, but then the lawmaker said that it would be fine if they slept with foreigners who were the same race.
Degtyaryov appeared to be doing damage control after lawmaker Tamara Pletnyova warned Russian women Wednesday to think twice before entering into casual relationships with foreign tourists because they may end up rearing their children alone. "I hope to God that there would be more love stories, more children, more mixed unions". "They are abandoned, and that's it, they stay here with mum". Pletnyova claims she's in favor of Russian women marrying "out of love regardless of their ethnicity", and insists that she is concerned about the well-being of mix-raced children who could face discrimination.
Federation Internationale de Football Association and the Russia 2018 organising committee did not immediately respond to a request for comment about Pletynova's remarks.
Pletnyova is a lawmaker for the KPRF Communist Party, a nominally opposition party that backs President Vladimir Putin's Kremlin on most key issues.