Antenatal Care is the care a woman receives throughout her pregnancy

It provides an opportunity to reach pregnant women with multiple interventions, including:

Source - http://www.who.int/pmnch/media/publications/oanfullreport.pdf

Four antenatal visits must be ensured during pregnancy

This is according to a new approach established by the World Health Organisation (WHO) in 2002, called focused antenatal care (FANC):

First visit Beyond 16 weeks of pregnancy
Second visit Between 24 and 28 weeks
Third visit Between 30 and 32 weeks
Fourth visit Between 36 and 40 weeks.