Biological and Clinical Sciences Research Journal
ISSN:
2708-2261
www.bcsrj.com
DOI:
https://doi.org/10.47264/bcsrj0201012
Biol. Clin.
Sci. Res. J., Volume, 2020: e012
PLACENTAL
THICKNESS AND ITS CORRELATION TO GESTATIONAL AGE ESTIMATED BY FOETAL GROWTH
PARAMETERS-A CROSS SECTIONAL ULTRASONOGRAPHIC STUDY
AHMAD M*1,
ANJUM MN2, MUZAFFAR A1, AYUB S*3, SIDDIQUE Z1,
MUBEEN I2
1Social Security Teaching
Hospital, Multan Road, Lahore, Pakistan
2Radiology Research
Section, The University of Lahore, Lahore, Pakistan
3Gynaecologist &
Obstetrician, Hameed Latif
Hospital, Lahore, Pakistan
*Corresponding
author email: drahmad6666@gmail.com, drsadafahmad6@gmail.com
Abstract
The placenta is a meterno-fetal organ
and starts developing on the 5th week from chorionic villi
at the implantation site. The placenta continues to increase in thickness and
hence its thickness can be used to indicate the gestational age when the last
menstruation date is not confirmed. The purpose of the study was to find out
the correlation of placental thickness to the gestational age estimated by
growth parameters of the fetus. The study was a cross-sectional analytical
study conducted on 2000 participants. The study was conducted in the Department
of Radiology Social Security Hospital, Multan Chungi
Lahore. The inclusion-exclusion criteria were established and participants were
observed using a Toshiba ultrasonography machine. The
subjects were placed supine and placental thickness was measured to the
accuracy of 1mm. Pearson’s correlation was applied to find out the correlation
between placental thickness and gestational age of the participants. The mean
age of the participants was 28.37 + 4.6. The youngest participant was age 18 and
the eldest participant was age 40. The gestational age of the participants
included ranged between 12th week to 40th week.
Pearson’s correlation score indicated that the correlation value 0.896. Which
indicated that the placental thickness and gestational age were strongly
correlated? The P-value < 0.05 indicated that the results were significant.
The study concluded a strong correlation between gestational age and placental
thickness of the fetus. The thickness of the placenta increased with an
increase in gestational age and hence could be used as a predictor and a
parameter of gestational age prediction when the last menstruation is uncertain
or is unknown.
Keywords: placental thickness,
radiology, immunological functions, gestational age, correlation
Introduction
Placenta
is a discoid shaped fetal organ that exhibits important metabolic and
endocrine, immunological functions. It provides a physiological link between
mother and fetus and serves as a passage for nutrition and respiration (Robinson
and Alasia Osuoabo, 2019). The placenta starts developing
on 5th week from the chorionic villi at
the site of implantation and by 9th to 10th week can be
seen through ultrasound. At 16th
week the placenta reaches its ultimate thickness and continues to grow in
diameter until the end of the third trimester (Khalid,
2009). Foetal growth parameters such as biparietal
diameter (BPD), head circumference (HC), abdominal circumference (AC) and
femoral length (FL) are used to sonologically
estimate foetal weight (Karthikeyan
et al., 2012a). In
circumstances when these parameters can’t be identified the estimation of placental
age becomes a problem. In conditions such as the rupture of membrane, breech
presentation, multiple gestation there may be a change in the shape of the foetal head and BPD cannot be accurately measured (Noor
et al., 2018). Placental
thickness can be used as a parameter for estimation of gestational age, as it
can be measured without much difficulty. Placenta is relatively immobile as
compared to the fetus while doing an ultrasound. It is the only factor that is
independent of the foetus for prediction of
gestational age (Mahale
et al., 2018). Estimation of
exact fetal age is essential for prediction of time of delivery and prompt
picking of any antenatal anomaly. Since years prediction of gestational age is
relied on the last menstrual period date, however according to literature only
56% of the females are able to retrieve the last menstrual period date with
complete certainty. If uncomplicated this forgetfulness might not cost much,
but in complicated pregnancies knowledge of accurate fetal age is crucial.
Addition of placental thickness as a marker of fetal age and growth parameters
will add to the safety of mother and child. Hence this study will be conducted
to find out the correlation of placental thickness with fetal age and growth
parameters.
Methodology
This cross
sectional analytical study was conducted at the Department of Radiology Social Security Hospital, Multan Chungi Lahore. The sample size was fixed to 2000 using 95%
of level of significance, 60% power of test and 5% margin of error. The
non-probability consecutive sampling technique was used to collect the required
sample. Inclusion criteria for the study was as follows; Singleton pregnancies,
11-40 weeks, the known last menstrual period, a history of regular
menstruation. Whereas the exclusion criteria was as follows; Maternal Disease
e.g. gestational diabetes, hypertension (Systemic hypertension and Pregnancy
induced hypertension), Anaemia, Foetal
anomalies, palcenta previa,
placental anomalies and poor visualization of the placenta, Multiple
pregnancies and last menstrual period not known or irregular menstrual periods (Karthikeyan
et al., 2012a). Toshiba Ultrasonography machine was used to examine the subjects.
Each foetus was measured only once during the whole
study. The transabdominal scanner was used to find
out the foetal anomaly if there is any. The
gestational age was determined by measuring the biparietal
diameter, the abdominal circumference, the crown rump length, the head
circumference and the femur length. The placental thickness was measured at the
level of the umbilical cord insertion; the maximum thickness was noted in the
cross section. Each placenta was measured to a 1 mm precision, at its greatest
thickness, which is perpendicular to the uterine wall. The uterine myometrium and the retroplacental
veins were excluded. The subjects were positioned supine and full bladder was
ensured at the time of taking measurements. The rules and regulations devised
by ethical committee of University of Lahore were followed while conducting the
study and rights of the subjects were respected. Written informed consent was
signed by all the participants and all the confidentiality of the gathered data
was ensured. The subjects were informed that the study procedure includes no
harm to them and is a part of regular examination. Subjects were moreover
informed that they were free to withdraw at any time during the process of the
study. Data in laptop was kept under password. After obtaining the informed consent patients were enrolled in the
study. Demographic data was collected prior conducting the required
examinations. Ultrasonographic measurements of
fetal growth parameters i.e. femur length, biparietal
diameter, head circumference, abdominal circumference were taken and compared
to the placental thickness. All data collected was mentioned in a
questionnaire. Data was analysed using SPSS version
21. Quantitative variables were described as mean and SD. Whereas
qualitative variables were described as frequency and percentage and Pearson’s
correlation was calculated to find-out the relationship between placental
thickness and gestational age estimated by fetal growth parameters.
P-value≤0.05 will be taken as significant.
Results
The data
comprised of 2000 women. Mean age + S.D of the participants were 28.37 +
4.69. The youngest participant was of age 18 and the eldest participant was of
age 40. Biparietal diameter, abdominal circumference,
femur length and head circumference was measured to calculate the gestational
age and the results were correlated with placental thickness to estimate the
gestational age. The mean results of growth parameters were as follows; Biparietal diameter 76.59 + 17.60, abdominal
circumference 268.42 + 91.48, femur length 59.30 + 15.74, head
circumference 280.11 + 61.69, placental thickness 31.03 + 6.83.
The maximum gestational age of the participants was 40 weeks and the minimum
gestational age of the participants was 12 weeks. The mean gestational age of
the participants was 30.98 + 6.64 weeks. The correlation between
placental thickness and gestational age was calculated using Pearson’s
correlation and the correlation score of 0.896 indicated a strong correlation
between placental thickness and gestational age. The positive value indicated
that placental thickness increased as gestational age increased. Moreover, the
P value < 0.05 indicated that the results of the Pearson’s
correlation were significant (Table 4).
Table 1: Mean Placental thickness during first
trimester of pregnancy (12th and 13th week)
|
Gestational
Week |
Number
of Subjects |
Mean
Placental Thickness |
|
12th |
7 |
11.42 + 9.03 |
|
13th |
15 |
13.33 + 1.68 |
Table 2: Mean Placental thickness during second
trimester of pregnancy (14th to 26th week)
|
Gestational
Week |
Number
of Subjects |
Mean
Placental Thickness |
|
14th |
26 |
14.42 + 2.50 |
|
15th |
11 |
16.90 + 3.98 |
|
16th |
20 |
16.55 + 1.66 |
|
17th |
12 |
17.00 + 2.13 |
|
18th |
51 |
18.76 + 2.86 |
|
19th |
30 |
19.23 + 2.95 |
|
20th |
36 |
19.77 + 2.41 |
|
21st |
37 |
22.25 + 3.52 |
|
22nd |
39 |
22.97 + 2.89 |
|
23rd |
42 |
24.66 + 3.25 |
|
24th |
17 |
23.41 +
2.00 |
|
25th |
25 |
25.16 + 2.71 |
|
26th |
34 |
26.08 + 2.47 |
Table 3: Mean Placental thickness during second
trimester of pregnancy (27th to 40th week)
|
Gestational
Week |
Number
of Subjects |
Mean
Placental Thickness |
|
27th |
56 |
26.78 + 2.95 |
|
28th |
56 |
27.96 + 2.62 |
|
29th |
93 |
29.35 +
2.67 |
|
30th |
73 |
30.04 + 3.38 |
|
31st |
99 |
31.32 + 2.38 |
|
32nd |
125 |
32.88 + 2.62 |
|
33rd |
156 |
33.09 +
2.87 |
|
34th |
206 |
34.03 + 2.83 |
|
35th |
184 |
35.18 + 2.50 |
|
36th |
166 |
35.65 + 3.19 |
|
37th |
193 |
36.48 + 3.13 |
|
38th |
116 |
36.93 + 3.76 |
|
39th |
59 |
38.30 + 4.49 |
|
40th |
06 |
37.16 + 2.40 |
Table
4: Correlation between Placental Thickness and Gestational Age
|
Correlation
between Placental Thickness and Gestational Age |
|||
|
|
Placental
thickness |
Gestational
Age |
|
|
Placental thickness |
Pearson Correlation |
1 |
.896** |
|
Sig. (2-tailed) |
|
.000 |
|
|
N |
2000 |
2000 |
|
|
Gestational Age |
Pearson Correlation |
.896** |
1 |
|
Sig. (2-tailed) |
.000 |
|
|
|
N |
2000 |
2000 |
|
|
**. Correlation is significant at the
0.01 level (2-tailed). |
|||
Discussion
Placental
thickness can be an accurate predictor of fetal growth and any retardation in
growth or early termination may be estimated by it. Any abnormality at fetal
level can be timely detected with the help of defined placental thickness at
any stage. It in this way can predict the abnormality when it is absent
clinically or symptomatically.
Placenta
is a materno-fetal organ and exhibits important
metabolic, immunological, thermoregulatory and endocrine functions. The
formation of placenta begins on 5th week from chorionic villi at implantation site and completes by 16th
week. Placenta is present in pebble grey color between week 8 and 20 of
pregnancy and achieves maximum growth at the term. Being a materno-fetal
organ its health indicates the health of fetus. After being detectable at 8th
week the placenta corresponds to the gestational age in weeks. Form current
study the placental thickness was measured at the level of umbilical cord
insertion (BaGhel
et al., 2015). In current
study the relationship between placental thickness and gestational age was
found to be linear. the results were consistent with the study by Naik and his colleagues (Naik
et al., 2021) placental
thickness increased with the increase in gestational age and increase in
thickness was observed in different participants presenting with different
trimesters i.e. week 12 to 39. In first trimester i.e. 12th week the
mean placental thickness was 11.42 + 9.03 which reached 13.33 +
1.68 at 13th week. In 2nd trimester the placental
thickness was observed to be 14.42 + 2.50 at earliest i.e. 14th
week and reached to the thickness of 26.08 + 2.47 at the end of 2nd
trimester i.e. 26th week. The placental thickness in the start of 3rd
trimester i.e. 27th week was observed to be 26.78 + 2.95
which increased to 38.30 + 4.49 at 39th week. An increase of
13mm in the thickness of placenta was observed in 1st trimester,
increase of 12mm in thickness of placenta was observed in 2nd
trimester whereas in 3rd trimester the increase in placental
thickness was observed to be 10mm. this indicated that the growth rate of
placenta was fastest in 1st trimester and it slowed down in 3rd
trimester. The placental thickness started decreasing after 39th
week of pregnancy as was observed in current study. The mean placental
thickness at 39th week was 38.30 + 4.49 which decreased to
37.16 + 2.40 at 40th week. The decline in placental thickness
was consistent with the previously conducted studies however the previously
conducted studies reported the decline in placental thickness to start after 36th
week of pregnancy (Naik
et al., 2021) whereas in
current study placenta continued to grow in thickness (although with decreased
rate) until 39th week. Placental thickness was not considered with
the location of placenta as the attachment site of placenta according to Kaushal et al
does not determine the thickness of placenta. A similar study was conducted by Karthikeyan et al
and they concluded that below normal thickness of placenta for gestational age
may be an indicator of a clinical condition and hence should be checked (Karthikeyan et al.,
2012b). Similarly thick placenta is
related with adverse outcomes (Miwa
et al., 2014). Placental
growth corresponds effectively for 2nd and 3rd trimesters
(Pant
and Dashottar, 2017). The placental
thickness corresponded to gestational age more specifically between 12th
to 26th week of fetal life. The results
were consistent with the study conducted by Suresh et al in 2017, according to their results placental growth was
consistent with gestational age during 12th to 24th week
of fetal life. Placental thickness can be related to the chromosomal
abnormalities (Hafner
et al., 2001) a study
conducted by a study conducted by Dombrowski et al (1992) indicated that the
placental thickness may falsely increase and decrease in polyhydramnios
and oligohydramnios respectively (Dombrowski
et al., 1992). In current
study correlation between placental thickness was
estimated and a strong correlation was observed. The Pearson’s correlation
value of 0.896 indicated that there was a strong correlation between placental
thickness and gestational age. The increase in thickness of placenta was
consistent with the increase in gestational age. The results were consistent
with the results of the study conducted by Adhikari et al in 2015 who observed a linear
correlation between the gestational age and placental thickness(Adhikari
et al., 2015). The placental thickness hence can be used to
predict the gestational age when the duration of pregnancy is not known or is
uncertain.
Conclusion
The study concluded a strong correlation between
gestational age and placental thickness of the fetus. The thickness of the
placenta increased with increase in gestational age and hence could be used as
a predictor and a parameter of gestational age prediction when the last
menstruation is uncertain or is unknown.
References
Adhikari, R., Deka, P. K., Tayal, A., and
Chettri, P. K. J. L. (2015). Ultrasonographic Evaluation of Placental Thickness
in Normal Singleton Pregnancies for Estimation of Gestation Age. 11,
7.0.