Human life stages, pregnancy stages, aging

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Homo sapiens

Unique characteristics of human reproduction and life history traits

"...humans exhibit relatively low per-copula fertility in association with concealed ovulation, an especially invasive form of hemochorial placentation coupled with copious mensruation compared to other primates, and remarkable fatness in babies, well beyond that of other mammals. Finally, humans have evolved substantial alterations in life history, with neurologically precocial yet physically altricial infants, remarkably short interbirth intervals despite the high cost to mothers of fetal development, a relatively elongated childhood, a greatly extended adult stage, and a postreproductive period in females associated with alloparental care."

Crespi BJ. The origins and evolution of genetic disease risk in modern humans. Ann N Y Acad Sci. 2010 Sep;1206:80-109.

Developmental stages, pregnancy

prenatal
- embryo MeSH
  - first trimester the beginning third of a human pregnancy, from the first day of the last normal menstrual period (menstruation) through the completion of 14 weeks (98 days) of gestation MeSH
    - pre-implantation embryo
      - zygote MeSH 1-cell embryo, fertilized ovum,
        Carnegie 1
      - cleavage MeSH dividing egg, 2-3 dpc, Carnegie 2
      - morula MeSH an early embryo that is a compact
        mass of about 16 blastomere;
        it resembles a cluster of mulberries
        with two types of cells,
        outer cells and inner cells
      - blastocyst MeSH 16-40-cell embryo, 2-4 dpc,
        Carnegie 3-5
        hatching 4-5 dpc, Carnegie 3
        
        attachment 6 dpc, Carnegie 4
        
        implantation 7-12 dpc, Carnegie 5a-5c
    - post implantation
      embryo 13-56 dpc, Carnegie 6-23;
      organogenesis takes place:
      hematopoiesis, development
      of nervous systems,
      development of heart, lungs
      and other internal organs,
      development of limbs
- fetus MeSH fetal period starts at 12th or at 14th weeks of gestation (according to different sources); the organogenesis is complete and the embryo is only grows in size
  - second trimester the middle third of a human pregnancy, from the beginning of the 15th through the 28th completed week (99 to 196 days) of gestation MeSH
  - third trimester the last third of a human pregnancy, from the beginning of the 29th through the 42nd completed week (197 to 294 days) of gestation MeSH
post natal
- neonate MeSH newborn, 0-30 days old
- infant MeSH a child between 1 and 23 months of age
  
  Tillett T. Environ Health Perspect. 2008 May
- child MeSH a person 6 to 12 years of age
- juvenile MeSH a person 13 to 18 years of age
- adult MeSH
  - middle aged MeSH a person 19 to 44 years of age
  - aged MeSH a person 65 through 79 years of age
    
    Barrett JR. Environ Health Perspect. 2009 January
  - elderly MeSH a person 80 years of age and older