The main causes of adverse pregnancy outcome(s) are reported to be maternal infection and placental, foetal, or uterine pathosis. Maternal infection and placental pathosis appear to be the most important causal factors, possibly causing pre-term labour, premature pre-term membrane rupture, or result in medically induced pregnancy interruption. There are reports of a link between poor maternal periodontal health and composite adverse pregnancy outcome of pre-term low birth weight (PLBW). however, the reason for such correlation is still not clear.