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Fetal Development

Third Trimester

26 weeks after conception
(28 weeks after the last menstrual period)

  • The fetus is about 10 inches long from crown to rump and weighs around 2 ½ pounds.
    [ View Picture ]
  • The eyes can perceive light, eyes can open and eyelashes are now present.
  • The woman may feel fetal respiratory movements as "hiccups".
  • Although immature, an otherwise normal fetus born at this time will often survive with expert care. In Alaska around 90% of fetuses born at 28 weeks gestation can survive with good care.

28 weeks after conception
(30 weeks after the last menstrual period)

  • The fetus is 10 ½ inches long from crown to rump and weighs almost 3 pounds.
  • The lungs develop to the point where breathing air is possible, although help is usually needed. In Alaska, with good care, the survival rate is 96% or better for fetuses of 29 weeks gestation or more.

30 weeks after conception
(32 weeks after the last menstrual period)

  • The fetus is about 11 inches long from crown to rump and generally weighs more than 3 pounds.
    [ View Picture ]
  • The skin is pink and no longer so transparent.
  • Toenails are now present.
  • From this stage on, fetal development is essentially complete, and growth is the primary change noted.

32 weeks after conception
(34 weeks after the last menstrual period)

  • The fetus is about 12 inches long from crown to rump and generally weighs 4 to 4 ½ pounds.
  • Eyes close during sleep and open during alert times.
  • The skin becomes smoother and pink.

34 weeks after conception
(36 weeks after the last menstrual period)

  • The fetus is 13 inches long from crown to rump and generally weighs about 5 to 5½ pounds.
    [ View Picture ]
  • Scalp hair is silky and lays against the head.
  • Muscle tone improves so the fetus can turn and lift its head.

36 weeks after conception
(38 weeks after the last menstrual period)

  • The fetus is 13 ½ inches long from crown to rump and generally weighs between 5 ½ to 6 ½ pounds.
  • Lungs are usually mature.
  • The fetus can grasp firmly.
  • The fetus turns toward light sources.
  • The fetus is gaining about ½ ounce per day.

38 weeks after conception
(40 weeks after the last menstrual period)

  • The fetus averages 14 ½ inches from crown to rump and an average of 20 inches in length from head to toe. [ View Picture ]
  • The average weight is around 7 ½ pounds.
  • This is a "full-term" fetus ready to be born.

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