[Suicide Junkie]

You could check settings.txt, and look for the "Empire Starting Percent Reproduction" setting.

Normally it is set to 10
If you have -9% to reproduction, you subtract and are left with 1%.

If you have taken a negative to environmental resistance, you get -1% repro per 5% taken out.

If your base reproduction rate is zero, your pop can never grow without artificial assistance.