The gestation period for giant pandas is believed to be three to five months. At this park, the shortest on our record was 93 days, while the longest was 163, showing a nearly two entire months’ difference. It has been found that the period can vary greatly among individuals. This is due to the unique reproductive mechanism in pandas known as delayed implantation.*

*Delayed implantation: A form of implantation observed in certain mammals. In this process, the embryo remains in a state of suspended dormancy until certain criteria are met, only when it continues on to implantation and placental formation. This is seen in relatives of bears, including pandas, and marsupials.

• Gestation Periods

  Mother: Meimei		Mother: Rauhin
  Birth Year	Gestation Period	Birth Year	Gestation Period
  2000	103 days	2008	138 days
  2001	93 days	2010	136 days
  2003	109 days	2012	129 days
  2005	139 days	2014	136 days
  2006	117 days	2016	136 days
  		2018	128 days
  		2020	163 days
  Average	112 days	Average	134 days
  Shortest	93 days	Shortest	128 days
  Longest	139 days	Longest	163 days

• Birth Estimation Table

  Mother	Birth Year	Days from First Signs to Birth
  		Decrease in fecal volume (less than 5kg)	Urinary pregnanediol peak	Continual increase in sleep duration
  Meimei	2000	24	20	26
  	2001	21	23	14
  	2003	21	22	24
  	2005	25	21	25
  	2006	22	22	23
  	Mean ± standard deviation	22.6±1.8	21.6±1.1	22.4±4.8
  Rauhin	2008	21	20	31
  	2010	23	25	31
  	2012	23	27	31
  	2014	27	20	29
  	2016	22	21	27
  	2018	22	23	27
  	2020	21	17	23
  	Mean ± standard deviation	22.7±2.1	21.9±3.4	28.4±3.0
  Meimei・Rauhin	Mean ± standard deviation	22.7±1.9	21.8±2.6	25.9±4.8

From 2010 on, the survival rate of panda babies in captivity has soared to 88%. This is believed to be due to established rearing techniques for the mother and child during the first week after birth, when the risk of death is highest. Estimating the date of birth is a crucial point in rearing management for newly born cubs and their mothers. Here we utilize three primary indicators to estimate due dates based on our past experience.

• ① Dramatic decrease in fecal volume (5 kg)
• ② Urinary pregnanediol (in the form of PDG) peak
• ③ Continual increase in sleep duration

These indicators appear in the order of increased sleep duration, decrease in fecal volume, and urinary pregnanediol peak. The decrease in fecal volume is believed to be the most reliable sign, as there is minimal variation. At the park, after estimating the date of birth based on these three indicators, we then conclude that a female is about to give birth when she grows restless, her vulva looks swelling, and she is seen frequently licking it. The ability to predict the date of birth allows us to well in time arrange the environment for the mother to give birth and raise the baby.

Fluctuations in Time Spent on Sleeping / Eating
(before Rauhin gave birth in 2020)

Fluctuations in Fecal Volume and Urinary Pregnanediol
(before Rauhin gave birth in 2020)