DTM: Which Stage Has the Greatest Gap Between Birth and Death Rates

The gap between birth rate and death rate is greatest in late stage 2. Death rates have already fallen sharply, but birth rates are still high, so natural increase peaks.

Stage by stage

• Stage 1: both rates high and roughly equal. Gap is small.
• Early stage 2: death rate starts to fall, birth rate still high. Gap is opening.
• Late stage 2: death rate has fallen a lot, birth rate has barely moved. Gap is widest.
• Stage 3: birth rate falls toward the death rate. Gap is closing, though growth is still positive.
• Stage 4: both low. Gap is small.
• Stage 5 (proposed): birth rate below death rate, so the gap turns negative.

Related question: greatest decline in death rate

The steepest fall in death rate is in stage 2, driven by sanitation, food supply and medicine. Fertility declines later, in stage 3.

Common traps

• Picking stage 3. Growth is still fast, but the gap is already shrinking.
• Picking early stage 2. Death rate has only just started to drop.
• Mixing up the gap with total population. Total population keeps rising through stage 3 and into stage 4 because of momentum.

One-minute recap

• Widest gap: late stage 2.
• Steepest death-rate fall: stage 2.
• Birth rate falls in stage 3, closing the gap.