Topic
The Prophet encouraged marrying and having children, but this is not a strategy of takeover, and fertility in Muslim countries has fallen sharply.
What it means
A hadith in Abu Dawud tells men to marry women who are loving and fertile, “for I will boast of your numbers before the other nations”. The family and children are praised in the Quran (25:74), and contraception was allowed by most jurists (see azl).
What the sources say
The claim that Muslims plan to take over by having children is not part of the faith. Fertility rates in Iran, Turkey, Tunisia and other Muslim-majority countries have fallen close to or below replacement level.