|Year : 2021 | Volume
| Issue : 4 | Page : 610-615
Association of placental weight with birth weight, gestational age, and risk factors related to maternal morbidity, diet, activity, and rest
Asha K Pratinidhi1, Avinash H Salunkhe2, Jyoti A Salunkhe1, Satish V Kakade1, Nanada Patil3, Nitin S Kshirsagar4
1 Department of Community Medicine, KIMS, Krishna Institute of Medical Sciences Deemed to be University, Karad, Maharashtra, India
2 Krishna Institute of Nursing Sciences, Karad, Maharashtra, India
3 Department of Pathology, KIMS, Krishna Institute of Medical Sciences Deemed to be University, Karad, Maharashtra, India
4 Department of OBG, Krishna Hospital and MRC, Karad, Maharashtra, India
|Date of Submission||07-May-2020|
|Date of Decision||22-Sep-2021|
|Date of Acceptance||26-Oct-2021|
|Date of Web Publication||24-Jun-2022|
Dr. Avinash H Salunkhe
Professor and Vice Principal, Krishna Institute of Nursing Sciences, Karad, Maharastra
Source of Support: None, Conflict of Interest: None
Background: Placental weight and its relationship to infant size at birth have been studied for more than a century. A low placental weight is associated with the medical complications in the mother. The risk of essential hypertension in adult life falls with increasing birth weight and rises with increasing placental weight and that the mothers at highest risk are those with a high placental weight relative to birth weight-that is, a high placental ratio. Aims/Objective: To study association of placental weight with birth weight, gestational age and maternal morbidity, diet, activity and rest. Settings and Design / Methods and Material: A cohort of 1876 apparently healthy pregnant women registered and attending antenatal clinic of Krishna Hospital was studied to find out the correlation of the placental weight with the LBW and preterm births and their association with selected maternal risk factors. Statistical Analysis Used: Correlation (r), Chi-square test, Analysis of Variance (ANOVA) and Boneferroni test, Unpaired 't' test, were used. Results: There was a statistically significant association of the mean placental weight with the mean birth weight and proportion of LBW of the baby as indicated by ANOVA test. (F= 29.627; p<0.001) and (χ2 =102.6; p<0.001) respectively. There was a statistically significant association of the mean placental weight with the mean gestational period of the baby and proportion of the preterm births as indicated by ANOVA test. (F= 7.694; p<0.001) and (χ2=18.377;p<0.001) respectively. Daily frequency of meals < 4, antenatal morbidity of preeclampsia, PIH and APH were associated with lesser placental weight. Conclusion: There was a significant association of placental weight with birth weight, gestational age, maternal morbidity and frequency of maternal meals.
Keywords: Birth weight to placental weight ratio, low birth weight, maternal morbidity, placental pathology, placental weight, preterm birth
|How to cite this article:|
Pratinidhi AK, Salunkhe AH, Salunkhe JA, Kakade SV, Patil N, Kshirsagar NS. Association of placental weight with birth weight, gestational age, and risk factors related to maternal morbidity, diet, activity, and rest. J Datta Meghe Inst Med Sci Univ 2021;16:610-5
|How to cite this URL:|
Pratinidhi AK, Salunkhe AH, Salunkhe JA, Kakade SV, Patil N, Kshirsagar NS. Association of placental weight with birth weight, gestational age, and risk factors related to maternal morbidity, diet, activity, and rest. J Datta Meghe Inst Med Sci Univ [serial online] 2021 [cited 2022 Aug 16];16:610-5. Available from: http://www.journaldmims.com/text.asp?2021/16/4/610/348088
| Introduction|| |
The placenta presents two surfaces, maternal showing cotyledons and fetal presenting the umbilical cord attachment. It weighs about 1/6th of fetal weight (1:6), and this ratio is fairly constant. Placenta is the most accurate record of the infant's prenatal experience. It is a unique organ and is directly related to growth and development of the fetus. Placental pathology can lead to problems in the growth and development of the fetus. Barker et al. reported that altered growth of the placenta was a predictor of maternal medical diseases. Other factors such as race and socioeconomic status also affect the placental weight. The importance of maternal nutrition as a determinant of placental weight to birth weight (BW) ratio is disputed. In India, about one-third of the babies born belongs to the low BW (LBW) category. These infants are susceptible to hypoxia, fetal distress, long-term handicap, and fetal death. LBW and preterm birth represents major public health problems in developing countries and are the major determinants of perinatal survival as well as infant morbidity and mortality., A study was therefore undertaken to know the relationship of placental weight with BW, preterm births, maternal morbidity, diet, activity, and rest. Furthermore, an attempt was made to find out the association of placental pathology to maternal and fetal morbidity in selected cases.
| Subjects and Methods|| |
A cohort of 1876 apparently healthy pregnant women registered and attending antenatal clinic of Krishna Hospital was studied to find out the correlation of the placental weight with the LBW and preterm births and their association with selected maternal risk factors. Enrolment of eligible pregnancies at Krishna Hospital Karad was undertaken from November 1, 2013 to December 31, 2015. As per the inclusion and exclusion criteria, the maternal factors, weight of placenta, and weight of new-born and gestational age were studied. The placentae were collected soon after separating the baby from the umbilical cord. The weights of the new-born babies and placenta were taken with the help of digital weighing scale accurately (Vijay digital baby weighing scale, India). The gestational age were calculated from the last date of menstrual period.
Antenatal morbidity was recorded for the entire cohort of 1876 women in addition specific information about maternal diet, occupation, hours of sleep at night, and rest during day time was collected from randomly selected subsample of 380 women. A total of 27 singleton birth placentae were studied where obvious morphological abnormalities were suspected at the time of delivery. Placental factors studied were physical abnormalities (e.g., infract, mass, vascular thrombosis, retro placental hematoma, amnion nodosum, abnormal colorations or ossification, malorder), small or large placental size or weight for gestational age or abnormalities of placental shape, umbilical cord lesions (e.g., thrombosis, torsion, true knot, single artery, and absence of Wharton's jelly), length of umbilical cord (short-length <32 cm at term and long-total length >100 cm) marginal or velamentous cord insertion, abnormal coiling (e.g., over coiled, under coiled, or flat cord), and placental weight. The present study was approved by the Institutional Ethics Committee. Informed consent was obtained from the pregnant women.
Statistical analysis was carried out using SPSS-20 (IBM SPSS, Bangalore, India). The Pearson Correlation coefficient 'r', Chi-square test, analysis of variance (ANOVA) and Boneferroni test, unpaired'-test, were used, P < 0.05 considered as statistically significant.
| Results|| |
Placental weight and birth weight
The mean placental weight was 479.4 g (g) with a standard deviation (SD) of ±50.0 g minimum weight was 200 g and maximum was 600 g. There was a statistically significant association of placental weight and the mean BW of the baby as indicated by ANOVA test. (F = 29.627; P < 0.001) One-way ordinary ANOVA revealed a significant increasing trend in the mean BW with increasing placental weight. According to Bonferroni multiple comparison test, BWs in placental weight groups of >400 g were significantly higher than the mean BW in placental weight group of ≤400 g (P < 0.001). BW to placental weight ratio for entire cohort was 5.50 with SD of 2.2. There was also a statistically significant relation between placental weight and proportion of LBW as indicated by the Chi-square test (χ2 = 102.6; P < 0.001). The Pearson correlation between placental weight and the BW was statistically significant (Pearson Correlation® = 0.2523; 95% confidence interval [CI]: 0.1933–0.3095 [P < 0.001]).
Placental weight and gestational age
There was a statistically significant association of placental weight and the mean gestational period of the baby as indicated by the ANOVA test (F = 7.694; P < 0.001). One-way ordinary ANOVA revealed that there was a significant increasing trend in the gestational period with increasing placental weight (F = 7.694; P < 0.001). According to Bonferroni multiple comparison test, gestational period in placental weight groups >400 g was significantly higher than the gestational period in placental weight group ≤400 g (P < 0.001). There was also a significant relation between placental weight and proportion of preterm births as indicated by the Chi-square test (χ2 = 18.377; P < 0.001). The Pearson correlation between placental weight and the gestational age was statistically significant (Pearson Correlation® = 0.1098; 95% CI: 0.04807–0.1706; [P = 0.005]) [Table 1].
|Table 1: Placental weight and low-birth weight and preterm births (n=1876)|
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There was a significantly higher mean placental weight, BW, and gestational age when the number of meals per day by pregnant women was four or more [Table 2] unpaired t-test revealed t = 2.637; P = 0.0087 for mean placental weight, t = 14.234; P < 0.001 for mean BW and; t = 4.008; P < 0.001 for the mean gestational age [Table 2].
|Table 2: Frequency of meals by mother and mean placental weight, birth weight, and gestational age (n=380)|
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The mean placental weight did not show any significant association with the type of work [Table 3] (ANOVA F = 0.013; P = 0.987), but the mean BW and the mean gestational age showed statistically significant association with the type of work (ANOVA F = 5.530, P = 0.004) (ANOVA F = 6.528, P = 0.002) for mean BW. The Bonferroni multiple comparison test revealed that among all comparisons there was a statistically significant difference (P = 0.010) in heavy work versus moderate work with BW. Whereas the type of work and mean gestational age showed significant difference for sedentary, moderate, and also heavy work. The gestational age decreased as the workload increased [Table 3].
|Table 3: Type of work during pregnancy and mean placental weight, birth weight, and gestational age (n=380)|
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The mean placental weight and mean gestational age did not show any significant association with duration of sleep or rest. However, when the mothers had a night sleep of <6 h, the mean BW was significantly lower, i.e., (2290.3 ± 542.0) as compared to 2740.5 g ± 467.2 g with a sleep of 6 h or more (unpaired t-test, t = 4.770; P < 0.001). The BW showed apparent but not significant higher values if pregnant women were able to take rest during day time of 2 h or more [Table 4].
|Table 4: Maternal rest and mean placental weight, birth weight, and gestational age (n=380)|
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Out of 1876 mothers, 504 (26.9%) had some morbidity, whereas in 1372 (73.15) mothers, no morbidity was observed [Table 5], preeclampsia was present in 161 (8.6%) pregnant women and was the most common morbidity during pregnancy followed by hypermeasisgravidum in 134 (7.1%). There was a statistically significant difference between mean placental weight and antenatal morbidity (ANOVA F = 7.091, P < 0.001). The Bonferroni multiple comparison test revealed that there was association between no morbidity versus pregnancy-induced hypertension (PIH) versus preeclapsia (P < 0.001), (P = 0.006). Lower mean placental weight was observed in preeclampsia, PIH, and antepartum hemorrhage (APH). The Bonferroni multiple comparison test revealed significant difference (P < 0.001), for PIH and (P = 0.006) for preeclampsia as compared to no morbidity group. The lower mean placental weight observed for APH was not significant. There was significantly lower mean BW when any antenatal morbidity was present (ANOVA F = 4.851, P < 0.001). The Bonferroni multiple compression test revealed that among all comparisons only for preeclampsia the difference was significant (P < 0.001).
|Table 5: Maternal morbidity, placental weight, birth weight, and gestational age (n=1876)|
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There was a statistically significant difference between mean gestational age and antenatal morbidity (ANOVA F = 9.526, P < 0.001). The Bonferroni multiple comparison test revealed that among all comparisons no morbidity versus APH versus preeclampsia was statistically significant (P < 0.001), (P = 043). The number of mother with tuberculosis and malaria were only two each, and hence, their association with placental weight, BW, and gestational period could not be ascertained [Table 5].
Except for a history of abortion and Lower Segment Caesarian Section (LSCS), history of epilepsy and polyhydraminous showing apparent naked eye aberration in the placenta, 75% pregnancies with other conditions showing placental variation were associated with LBW in the baby. Total proportion of LBW of 50% and preterm births of 44.4% was seen among "27" babies born to mothers whose placentae showed gross abnormality on naked eye examination and sent for histopathological examination [Table 6].
|Table 6: Placental pathology, mean placental weight, birth weight, and gestational age with standard deviation of singleton deliveries (n=27)|
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Classification of placental histopathological findings
Out of "27" singleton placentae five placentae had syncitial knot, utero-placental insufficiency (UPI) with perivillious fibrin five had intervillous hemorrhage with mild UPI, and two had infract with UPI. Three placentae had calcification and two had chorioamniotis. The total 17 placentae had mild-to-severe histopathologically abnormality, i.e., UPI, calcification, infract, inflammation, and chorioamniotis. There were ten placentae (10) which did not show significant histopathology.
| Discussion|| |
The range of mean placental weights reported by various workers was 477.6 g to 672 g.,,,,,,,,, The mean placental weight observed in the present study was 479.4 g with a SD of ±50.0 g. This was similar to 477.6 g reported in Bayero university, Kano, Northern Nigeria and 470 g in Ukraine. This was lesser than 543 g recorded in Nigeria, 565 g in South-West Nigeria, 590 g in North-west Nigeria, 587 g in Indonesia, 519 g in India, 630 g in South-east Nigeria, 630 g in Western Europe, 670 g in North Central Nigeria, and 672 g reported in Norway. Variations in the technique of preparing and weighing the placenta, maternal nutritional status together with cord clamping time may be responsible for the different values reported in various studies.
The mean BW in the present study was 2610.3 g ± 482.4 g. This was lesser as compared to the range of mean BW of 2867.4 go to 3425 g as reported by various workers.,,,,,,,, The mean birth weight of babies born in Northern Nigeria was 2867.4 g, 3096 g was in Nigeria, 3120 g was in Ethiopia,  3103 g was in the Afro Caribbean region, and 3140 g was in India, 3275 g was in North-west Nigeria, 3425 g, 3382 g, and 3400 g was in Ukraine, Western Europe, and Eastern Nigeria, respectively. Variations in maternal health status and nutrition may be responsible for the slight differences here and there among study populations.
Furthermore, there was a positive correlation (P < 0.001) between placenta and BW in our study; this signifies that as placental weight increased, BW is also increased.
This correlation was also reported by Panti et al. Positive correlations have been documented in other studies.,,,
The mean gestational age in the present study was 264.1 ± 15.7 days, i.e., 37.73 weeks and rate of preterm births was 19.5%, which was higher than the rates of 9.97%–14.2% reported by other workers.,,,, Similar results were seen in a study done by Samiran Bisai. In Kolkata, India, the researchers found that among all births, 9.97% were preterm (<37 weeks of gestation) and 90.03% were term (37–41 weeks gestational age) neonates. Similarly, among all LBW babies, 80.16% were term and 19.84% were preterm.
Theresia B. Temu et al. in Northern-eastern Tanzania noted a high prevalence of preterm deliveries, i.e., 14.2%. In another study by Mahande MJ in Northern Tanzania, which was a registry-based cohort study, which was conducted in similar setting using hospital birth registry instead of data. The estimated prevalence of preterm delivery was higher than that reported in Tanzania of 12% and 11%, respectively, by Watson JD Kinney MV at London, UK.
Based on the data from 184 countries, the global average preterm birth rate in 2010 was 11.1%. Preterm birth rates varied widely between countries. The highest rates of preterm birth were in South-eastern Asia and sub-Saharan Africa (13.5% and 12.3% of all live births, respectively). Studies revealed incidence to be higher in developing countries than in developed countries. At a national level, the estimated preterm birth rate ranged from about 5% to 18%.
The present study improved our understanding of the role of the placenta in fetal growth, a complex process that involves multiple maternal and fetal factors. Apart from placental factors, it is possible that other adverse risk factors that contribute to preterm birth also impact fetal growth. Intrauterine inflammation is thought to induce preterm birth as well as poor fetal growth., Third trimester growth is shortened among infants born preterm hence many of them are also LBW.
The placental supply of maternal nutrients becomes more with increased placental mass leading to a larger placental and subsequently larger infant size. Our interpretation is biologically plausible. Placental size is correlated with the capacity for nutrient transfer and increases steadily throughout gestation.
In animal studies of sheep, enlarged placentas by diet manipulation produced larger lambs. In horses, where size differs by breed, when fertilized embryos from smaller breeds are implanted in larger breeds, the placental and fetal weights are larger than if the embryos remained in the smaller breed. This demonstrates that placental weight and surface area can enhance fetal size. In human epidemiological studies, maternal diet and energy intake can affect placental size., For example, women who fast during Ramadan during the last trimester have smaller placentas. Taken together, previous animal and epidemiologic studies suggest that maternal nutrition may influence fetal growth through placental weight.
In the present study, there was a significantly higher mean placental weight, BW and gestational age when the number of meals per day by pregnant women was four or more. The study conducted by Kadam at Sangli reported that to have a normal BW extraallowances of calories, proteins, vitamins, and minerals are required during pregnancy. If mother consumes food at least four times a day it can meet extra demands of pregnancy. Furthermore, maintaining blood glucose level in the mother is vital because glucose is the fetus's preferred fuel and because the fetus's blood glucose level is always lower than the mothers. That is why intake should be distributed throughout the day as reported by Lutz and Przytulski. Therefore, to assess dietary intake, mothers were asked about their diet frequency. All mothers had the two principal meals, i.e., lunch and dinner, but the difference in the frequency of having breakfast and evening snacks was observed. Mean BW of new-borns born to mothers consuming breakfast and evening snacks was more than those who skipped them. The observed difference was statistically significant in mothers who had breakfast, whereas marginally significant in those who had their evening snacks. This observation highlights the importance of advice on having breakfast and evening snacks, which is simpler to give as well as to follow. Farrow et al. in Avon in South-west England found a difference of 148 g between the mean BW of infants born to women with professional occupations and those with plant and machine operative jobs. However, no significant association with BW was observed.
There is growing evidence that the placenta plays a key role in fetal programming of cardio metabolic diseases. In addition to nutrient transport, the placenta also plays a key role in the production of hormones which can influence intrauterine and extrauterine growth.
Placental weight is one of the several physical parameters that may predict outcomes, including placental thickness, width, length, and cord placement position. Placental size may also increase due to remodeling from a prior injury. Thus, caution is needed when using placental weight alone to reflect placental function as a determinant of fetal growth.
Strengths of this study include its multiple prenatal and perinatal factors, measures of placental weight, as well as a wide range of potentially known confounders of preterm birth and fetal growth among a relatively large number of women.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Standring S. Gray's anatomy. In: The Anatomical Basis of Clinical Practice. 40th
ed. London UK: Churchill Livingstone, Elsevier; 2008. p. 176-177, 1302.
Moore KL, Persaud TV. The Developing Human, Clinically Oriented Embryology. 8th
ed. Philadelphia Pennsylvania: Saunders; 2009. p. 116-7, 123.
Barker DJ, Bull AR, Osmond C, Simmonds SJ. Fetal and placental size and risk of hypertension in adult life. BMJ 1990;301:259-62.
Dutta DC. Low Birth Weight Baby. Text Book of Obstetrics. 6th
ed. Kolkata: Central; 2004. p. 458-70.
Perry IJ, Beevers DG, Whincup PH, Bareford D. Predictors of ratio of placental weight to fetal weight in multiethnic community. BMJ 1995;310:436-9.
Edwards CR, Benediktsson R, Lindsay RS, Seckl JR. Dysfunction of placental glucocorticoid barrier: Link between fetal environment and adult hypertension? Lancet 1993;341:355-7.
McCormick MC. The contribution of low birth weight to infant mortality and childhood morbidity: Review. New England J Med 1985;312:82-90.
Conde-Agudelo A, Belizan JM, Diaz-Rossello JL. Epidemiology of fetal death in Latin America. Acta Obstetrics Gynecol Scand 2000;79:371-8.
Anas IY, Saleh MS. Birth weight and placental weight correlation of fulani ethnic group parturients in Nigeria. Br J Med Med Res 2014;4:1049-55.
Little RE, Zadorozhnaja TD, Hulchiy OP, Mendel NA, Shkyryak-Nyzhnyk ZA, Chyslovska N, et al
. Placental weight and its ratio to birthweight in a Ukrainian city. Early Hum Dev 2003;71:117-27.
Allagoa DO, Kotingo EL. Relationship between placenta weight and birth weight at the federal medical centre, Yenagoa. Int Res J Med Biomed Sci 2019;4:28-32.
Adebami OJ, Owa JA, Oyedeji GA, Oyelami OA, Omoniyi-Esan GO. Associations between placental and cord blood malaria infection and fetal malnutrition in an area of malaria holoendemicity. Am J Trop Med Hyg 2007;77:209-13.
Panti AA, Ekele BA, Nwobodo EI, Yakubu A. The relationship between the weight of the placenta and birth weight of the neonate in a Nigerian Hospital. Niger Med J 53:80-4.
Patimah S, Syauqi Y, Thaha AR. The Correlation between Placental Weight and Birth Weight. International Proceedings of Chemical, Biological and Environ mental Engineering, Strøm; 2015.
Manop J, Ounjai K, Alan G. Placenta weight and its ratio to birth weight in normal pregnancy at songkhlanagarind hospital. J Med Assoc Thai 2006;89:130-7.
Adinma JI, Agbai AO. Fetal birth weight in Africa. J ObstetGynaecol 1995;15:295-297.
Onche EP, Zaiyol ST, Ochigbo OA, Terkimbi UB, Avershima OA, Kuma HH. Placentabirth weight ratio at tem at Benue State University Teaching Hospital, Makurdi North Central Nigeria. Res Rep Gynaecol Obstet 2017;1:16-8.
Strøm-Roum EM, Haavaldsen C, Tanbo TG, Eskild A. Placental weight relative to birth weight in pregnancies with maternal diabetes. Acta Obstet Gynecol Scand 2013;92:783-9.
Tiruneh ST. Correlation between gross morphology of the human placenta and birth weight in normotensive and pre-eclamptic pregnancies in Northwest Ethiopia. Anatomy 2018;12:27-32.
Lurie S, Feinstein M, Mamet Y. Human fetalplacental weight ratio in normal singleton near-term pregnancies. Gynecol Obstet Invest 1999;48:155-7.
Sivarao S, Vidyadaran MK, Jammal ABE, Zainab S, Goh YM, Ramesh KN. Weight, Volume and Surface Area of Placenta of Normal Pregnant Women and their Relation to Maternal and Neonatal Parameters in Malay, Chinese and Indian Ethnic Groups 2002;23:691-6. DOI: 10.1053/plac.2002.0817,Pub Med.
Güler AE, Atasever M, Fidan U, Artürk E, Kinci MF, Bodur S. The relationships between pregnancy-associated protein A levels, placental localization and fetal birth weight. Obstetrics Gynecol Reproduct 2018;12:15-20.
Luque-Fernandez MA, Ananth CV, Jaddoe VW, Gaillard R, Albert PS, Schomaker M. Is the fetoplacental ratio a differential marker of fetal growth restriction in small for gestational age infants? Eur J Epidemiol 2015;30:331-41, 390.
Temu TB, Masenga G, Obure J, Mosha D, Mahande MJ. Maternal and obstetric risk factors associated with preterm delivery at a referral hospital in Northern-eastern Tanzania. Asian Pacific Journal of Reproduction 2016;5:365-70.
Mahande MJ, Daltveit AK, Obure J, Mmbaga BT, Masenga G, Manongi R, et al
. Recurrence of preterm birth and perinatal mortality in northern Tanzania: registry-based cohort study Trop Med Int Health 2013;8:962-7.
Watson JD, Weiss HA, Changalucha JM, Todd J, Gumodoka B, Bulmer J, et al
. Adverse birth outcomes in United Republic of Tanzania – impact and prevention of maternal risk factors Bull World Health Organ 2007; 85:9-18.
Kinney MV, Lawn JE, Howson CP, Belizan J. 15 Million preterm births annually: what has changed this year? Reprod Health, 2012. p. 28.
Blencowe H, Cousens S, Mikkel Z O estergaard, Chou D, Narwal AB, Adler A, et al
. National, regional, and worldwide estimates of preterm birth rates in the year 2010 with time trends since 1990 for selected countries: a systematic analysis and implications 2012;379:2162-72. doi: 10.1016/S0140-6736(12)60820-4. Available from: www.thelancet. com Vol 379 June 9, 2012. [Last accessed on 30 Dec 2016] .
Goldenberg RL, Hauth JC, Andrews WW. Intrauterine infection and preterm delivery. N Engl J Med 2000;342:1500-7.
Mestan K, Yu Y, Matoba N, Cerda S, Demmin B, et al
. Placental inflammatory response is associated with poor neonatal growth: Preterm birth cohort study. Journal of Pediatrics Published Apr 2010;125:e891-8.
Fowden AL, Ward JW, Wooding FP, Forhead AJ, Constancia M. Programming placental nutrient transport capacity. J Physiol 2006;572:5-15.
Thornburg KL, O'Tierney PF, Louey S. Review: The placenta is a programming agent for cardiovascular disease. Placenta 2010;31 Suppl: S54-9.
Jansson T, Powell TL. Role of the placenta in fetal programming: Underlying mechanisms and potential interventional approaches. Clin Sci (Lond) 2007;113:1-13.
Kadam YR, Chavan PV, Dhoble RV, Gore AD. Effect of cooking posture on birth weight. Muller J Med Sci Res 2014;5:34-8. [Full text]
Lutz C, Przytulski K. Life Cycle Nutrition: Pregnancy and Lactation. Nutrition and Diet Therapy, Evidence-Based Applications. 4th
ed. New Delhi: Jaypee Brothers Medical Publishers (P) Ltd.; 2008. p. 201.
Farrow A, Shea KM, Little RE. Birth weight of term infants and maternal occupation in a prospective cohort of pregnant women. The ALSPAC Study Team. Occup Environ Med 1998;55:18-23.
Murphy VE, Smith R, Giles WB, Clifton VL. Endocrine regulation of human fetal growth: The role of the mother, placenta, and fetus. Endocr Rev 2006;27:141-69.
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]