Even so, life for a newborn baby would be short were it not for a development that takes place in the womb when a fetus is only about four months old.
हालाँकि आम तौर पर देह बाह्‍य ऊतक को अस्वीकार करती है, गर्भ निषेचित डिम्ब के मामले में अपवाद करती है ।