When You Will Be Screened

The standard time for GDM screening is between 24 and 28 weeks of pregnancy.

That window is not arbitrary. Insulin resistance in pregnancy is driven by placental hormones, and their output rises as the pregnancy progresses. Test much earlier and the strain has not yet shown itself. Test much later and there is less of the pregnancy left in which to act.

If you have risk factors, you may be tested earlier as well — often at the first antenatal visit. A normal early test does not replace the one at 24 to 28 weeks. That trips people up: an early clear result feels like the matter is settled, and it is not, because GDM commonly appears later.

India's national data shows GDM in 19.2% of pregnancies before 20 weeks and 23.4% at or after 20 weeks, so both timings genuinely find cases.

In India, universal screening is the policy — every pregnant woman is offered the test rather than only those who look high risk. At a national prevalence above 20%, risk-based screening would miss a great many cases.

If you are booking late in pregnancy, ask for the test at your first visit rather than waiting for a window that has already passed.