Int J Med Sci 2018; 15(5):484-491. doi:10.7150/ijms.23107

Research Paper

Impact of placental weight and fetal/placental weight ratio Z score on fetal growth and the perinatal outcome

Yoshio Matsuda1,2✉, Toshiya Itoh3, Hiroaki Itoh3✉, Masaki Ogawa4, Kemal Sasaki5, Naohiro Kanayama3, Shigeki Matsubara6

1. Department of Obstetrics and Gynecology, Japan Community Health Care Organization (JCHO) Mishima General Hospital 2276 Yata Aza Fujikubo, Mishima- City, Shizuoka 411-0801 JAPAN
2. Department of Obstetrics and Gynecology, International University of Health and Welfare Hospital, 537-3 Iguchi Nasushiobara, Tochigi 329-2763 Japan
3. Department of Obstetrics and Gynecology, Hamamatsu University School of Medicine 1-20-1 Handayama, Higashi-ku, Hamamatsu city, Shizuoka, Japan 431-3192
4. Department of Obstetrics and Gynecology, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan
5. Faculty of Childhood Education, Yokohama Soei University, 1 Miho-cho, Midori-ku, Yokohama, Kanagawa 226-0015
6. Department of Obstetrics and Gynecology, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi 329-0498, Japan

Abstract

Objective: To classify the infants into 9 blocks based on the deviation of both placental weight (PW) and fetal/placental weight ratio (F/P) Z score and compared the incident rate of perinatal death in each of the small for date (SFD) vs. appropriate for date (AFD) vs. heavy for date (HFD) groups.

Methods: The study population consisted of 93,034 placentas/infants from women who vaginally delivered a singleton infant. They were classified into 3 groups according to infants' weight: SFD (n=3,379), AFD (n=81,143) and HFD (n=8,512). The population was classified into 9 blocks according to the combination of i) low vs. middle vs. high placental weight (PW: a sex-, parity- and gestational-age-specific placental weight) and ii) low vs. middle vs. high F/P. In both i) and ii), ± 1.28 standard deviations in the in the Z scores was used for classifying low vs. middle vs. high, with 3x3 making 9 blocks. We then determined whether or not the perinatal death in each block differed among the three groups (SFD vs. AFD vs. HFD).

Results: (1) The proportions of 'balanced growth of placenta and infant' (appropriate PW and F/P based on Z-score) were 37.6% in the SFD group, 78.8% in the AFD group, and 51.2% in HFD group. (2) The proportion of 'inappropriately heavy placenta' in the SFD group and that of 'inappropriately light placenta' in the HFD group were 0.3 and 0.4%, respectively, a very rare phenomenon. The proportions of 'inappropriately heavy placenta' and 'inappropriately light placenta' accounted for 4.1 and 5.5% in AFD group, respectively. (3) The rates of perinatal death in those with 'balanced growth of placenta and infant' were lowest in the SFD and AFD groups.

Conclusion: By showing the fact that perinatal death was lowest in cases with balanced fetal/ placental growth, we conclude that 9-block categorization of PW and F/P based on deviation in the Z-score may be a candidate factor employable for understanding fetal and placental growth and perinatal deaths.

Keywords: appropriate for date, fetal/placental weight ratio(F/P), heavy for date, placental weight, small for date, Z score

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How to cite this article:
Matsuda Y, Itoh T, Itoh H, Ogawa M, Sasaki K, Kanayama N, Matsubara S. Impact of placental weight and fetal/placental weight ratio Z score on fetal growth and the perinatal outcome. Int J Med Sci 2018; 15(5):484-491. doi:10.7150/ijms.23107. Available from http://www.medsci.org/v15p0484.htm