Winsberg ( 1973 ) described changes of ultrasound appearance of the placenta occurring after 36 weeks. He described appearance of rounded transonic areas in the placental tissue .
Spirt et al ( 1982 ) tried to correlate changes that take place in the placenta with gestational age and maternal disease. He found evidence of decreased calcification in multiparous women and no significant relationship between placental calcification and maternal age.
Kazzi et al (1983 ), Kumari et al ( 2001 ), Dudley et al ( 1993 ) found relationship between grade III placenta and small for gestation age .
Hills et al ( 1984 ) reported the delayed changes from grade 0 to grade I. They suggested that if grade 0 placenta presented after 33 weeks the pregnancy might associated with the gestational diabetes and Rh sensitization.
Hopper et al ( 1984 ) proposed that if grade I is seen prior to the 27 weeks, grade II prior to 32 weeks and grade III placenta prior to 34 weeks of gestation, the pregnancy is likely to be complicated with intrauterine growth restriction ( IUGR ) and preeclampsia.
Shweni ( 1986 ) found that grade I or grade II placenta at term is associated with Rh iso-immune disease.
Zhang LY et al ( 2005 ) grade III placenta before 37 weeks is associated with oligohydramnios and low birth weight and needs close monitoring.
Grannum et al ( 1979 ) classified placental maturity into four grades 0 - III, based on the ultrasound appearances placenta.Grading was based on the changes occurring in three zones of placenta : chorionic plate, placental substance and basal layer, as the pregnancy advances.
Grade - 0
Late 1st trimester-early 2nd trimester
Chorionic plate - Smooth, straight and well defined unbroken dense line.
Placental substance - Uniform homogeneous echotexture with out any echogenic areas
Basal layer - No basal layer echogenicities
Grade - 1
It is the earliest ultrasound changes of placental maturation.
Chorionic plate - Well-defined unbroken line, but may present fine undulation.
Placental substance - Few scattered echogenic areas appear within the placenta resulting in a loss of homogeneity.
Basal layer - No basal layer echogenicities.
Grade - 2
Notable changes in all the three layers
Chorionic plate - more marked indentations as compared to the grade 1
Placental substance - incompletely divided by the appearance of linear ( comma ) echogenic densities / line.
Basal layer - linear small echoes are arranged with their long axis parallel to the basal layer. Larger calcifications in a "dot-dash" configuration along the basilar plate ( basal stippling )
Basal echoes in the placenta are a hallmark of a grade ll placenta
Grade - 3
Is the late phase represents the mature placenta
Chorionic plate - Plate appears interrupted by indentations, which now extend to the basal layer and probably represent the inter cotyledon septa.
Placental substance - Placenta divided into compartments which presumably demarcate the cotyledons. The central portion of these compartments shows echo-spared or fallout areas.
Basal layer - Echogenic densities persist and become larger and denser
Chorionic plate indentation that extend all the way to the basal layer
Placental calcification -
The placenta stores calcium for the fetus. The degree of placental calcification has, therefore, been associated with maternal serum calcium levels.
Increased incidence of placental calcifications has been reported in pregnant women on calcium supplementation
There is an increased deposition of calcium in the placenta of women with severe pre-eclampsia and in fetal growth restriction.
Placental calcification Vs Maternal Age -
No statistically significant relationship between placental calcification and maternal age has been proven.
Placental calcification Vs Parity -
Placental calcification has a higher association with nulliparity as compared with multiparous women.
Placental calcification Vs Gestational age -
Incidence and degree of calcification correlates with the time of gestation. Calcification begins to increase at 29 weeks and continues to increase until term, with a relatively steep rise in the percentage of placentas showing calcification at 35 to 36 weeks.