how long does it take for a blue whale to give birth
Gestation lasts 10–11 months.
Blue whale
 Gestation lasts 10–11 months.
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Blue whale [SEP] Reproduction and birth
Pygmy blue whales were estimated to give birth every 2.6 years (95% CI=2.2–3.0). Pregnant females gain roughly 4% of their body weight daily, amounting to 60% of their overall body weight throughout summer foraging periods. Gestation lasts 10–11 months. No records of natural births are known, although a blue whale that ended up in Trincomalee harbor gave birth to a calf before being towed back to sea the following day.