One of the reasons I know this is that babies whose mothers have 12 or more weeks at home with them are more likely to get their vaccinations and their well checks in their first year, so those babies are more protected from deadly and disabling diseases.
こう申し上げる理由のひとつは 赤ちゃんと12週間以上 我が子と過ごすことのできる母親の子は 生後１年の間にワクチン接種と 健康診断を受ける可能性が高く 命に関わり障害の残るような病気から より守られているのです