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ORIGINAL ARTICLE
Year : 2021 | Volume
: 24
| Issue : 3 | Page : 345-354
Vitamin D and bone mineral status of newborn-maternal pair delivering at a tertiary hospital in Nigeria
HA Elechi1, A Oduwole2, HW Idris3, MB Faruk4, MA Alhaji1
1 Department of Paediatrics, College of Medical Sciences, University of Maiduguri, Maiduguri, Nigeria
2 Department of Paediatrics, College of Medicine, University of Lagos, Zaria, Nigeria
3 Department of Paediatrics College of Medicine, Ahmadu Bello University, Zaria, Nigeria
4 Department of Paediatrics, College of Medical Sciences, Abubakar Tafawa Balewa University, Bauchi, Nigeria
Correspondence Address:
Dr. H A Elechi
Department of Paediatrics, College of Medical Sciences, University of Maiduguri, Maiduguri
Nigeria
Source of Support: None, Conflict of Interest: None
CheckDOI: 10.4103/njcp.njcp_368_20
Abstract
Background: Vitamin D plays a vital role in the maintenance of bone health. The fetuses and exclusively breastfed neonates depend on maternal vitamin D store to meet their need. Widespread vitamin D deficiency among pregnant women have been reported with adverse fetal outcome. Nigeria lacks guideline on Vitamin D supplementation in pregnancy and infancy due to the paucity of data. We thus determined serum vitamin D of delivering mothers and their offsprings and other indicators of bone mineral health. Aims: This study aimed to determine serum Vitamin D and other indicators of bone mineral health of delivering mothers and their offspring. Material and Method: A cross-sectional study of delivering mothers and their newborns recruited consecutively until the minimal sample size was reached. Relevant information was obtained on a questionnaire. Maternal and cord serum vitamin D, calcium, albumin, phosphate, and alkaline phosphatase were determined. Data management was done using SPSS version 16.0. Results: Of the 84 newborn-mother pairs studied, 17 (20.2%) of the mothers were Vitamin D deficient and 23 (27.4%) insufficient. Seven (8.3%) of the mothers were hypocalcaemic and 3 (3.6%) hypophosphataemic, while 19 (22.6%) had elevated alkaline phosphatase. Only 15 (17.9%) of the neonates were vitamin D insufficient and none of them was vitamin D deficient, hypocalcaemic, hypophosphataemic nor had elevated alkaline phosphatase. There was strong positive correlation between cord and maternal blood vitamin D level (r = 0.740, P = < 0.001). Conclusion: Vitamin D deficiency and insufficiency is high among pregnant women in Maiduguri while insufficiency is common among the neonates. We recommend vitamin D supplementation to pregnant women and newborns in Maiduguri.
Keywords: Bone mineral health, cord-maternal ratio, newborn-maternal pair, vitamin D status
Introduction 
Vitamin D plays an important role in the maintenance of bone health through the regulation of calcium and phosphate metabolism.[1] This role is particularly important in the early stages of childhood which are characterized by rapid skeletal growth and development.[2] During intrauterine life, fetal bone mineral health is maintained through active transplacental transfer of calcium and phosphate. After birth, the newborn depends on the intrinsic regulatory system––vitamin D inclusive––to maintain calcium and phosphate homeostasis. The newborn vitamin D status, a reflection of maternal vitamin D status in late pregnancy, thus becomes an active player in the maintenance of bone mineral health of the neonate. Low maternal Vitamin D level in pregnancy has been linked to various adverse pregnancy and health outcomes in the offspring, including a higher risk of abortion, pre-eclampsia, gestational diabetes mellitus, low birth weight, neonatal hypocalcemia, impaired development, and rickets.[1],[3] In a longitudinal study in 2006, Javaid et al.[4] showed that a woman's vitamin D status during pregnancy may have effects on her child's skeletal development that persist long after infancy. The wide-spread of vitamin deficiency among pregnant women and its association with several adverse pregnancy outcomes led to the global movement for vitamin D supplementation in pregnancy.[5],[6] However, the World Health Organization (WHO) in 2019 made a paradigm shift on its earlier recommendations on vitamin D supplementation in pregnancy, citing inadequate evidence.[7] While the association of vitamin D deficiency in pregnancy with several adverse pregnancy outcomes (pre-eclampsia, gestational diabetes mellitus, preterm birth, etc) may be limited in evidence, the effect on bone mineral health of both mother and newborn seems incontrovertible. In Nigeria, there has been no policy statement neither for nor against vitamin D supplementation in pregnancy. This may be due to a dearth of representative data on the vitamin D status of the population in general and pregnant women in particular. There are very few studies on vitamin D status of pregnant women and their newborn in Nigeria despite the high incidence of hypocalcemia and hypocalcemic tetany in pregnancy in the country.[8],[9] The findings of the few (only two available) studies[10],[11] on vitamin D in pregnancy in Nigeria are conflicting. Studies from other tropical and subtropical countries like India,[12] China,[13] Iran,[14] however, have consistently documented a high prevalence of vitamin D deficiency and insufficiency among pregnant women and their newborns. We thus undertook this study to determine the vitamin D profile of pregnant women and their offspring at birth and the effect on the major minerals indicating bone health. The findings from this study will fill the knowledge gap in the area and will highlight the need or otherwise of vitamin D supplementation in pregnancy and newborn.
Materials and Method This hospital-based cross-sectional study was conducted at the labor ward of the University of Maiduguri Teaching Hospital. Maiduguri is a semi-arid zone lying between lat. 11°'5' N and long. 13°'09' E with sunny weather all through the year and an annual rainfall of 1.14 mm to 771.90 mm.[15] The dusty harmattan season which usually lasts 3-4 months extends between November and February. The labor ward takes delivery of an average of 3000 women per annum. Normal, uncomplicated vaginal delivery is usually discharged 24 hours after delivery while caesarian deliveries are discharged five days post-delivery.
All newborn-maternal pairs delivering at the labor ward of the University of Maiduguri Teaching Hospital who previously consented to the study were enrolled consecutively until the calculated minimum sample size was reached. Mothers on prophylactic Vitamin D or vitamin D-containing supplement, anticonvulsants, rifampicin, Isoniazid, and glucocorticoids were excluded.[16]
The minimum sample size was calculated using Formula for a quantitative outcome.[17] Value of 's' was taken from a study in India where a standard deviation of serum vitamin D among pregnant women were put at 9.3 ng/mL:[18]
where
n = the minimum sample size,
Z = 1.96 (Standard normal deviate at 95% confidence level),
S = Standard deviation of serum vitamin D among pregnant women,
d = Level of precision = 2 ng/ml, and
Therefore, the minimum sample size
= 83.0649
= 84 newborn-maternal pairs
Ethical clearance was obtained from the Research and Ethics Committee of the University of Maiduguri Teaching Hospital. Informed signed consent was obtained from each participating woman with the liberty to decline or opt-out of the research at any point in time with no consequence to the participant. The Vitamin D, Calcium, phosphate, and alkaline phosphatase status of mother-infant pair were disclosed to the Mothers via text messages and those with hypovitaminosis D and or hypocalcemia were advised appropriately.
Study procedure
Pregnant women in their third trimester were recruited into the study at the antenatal clinic. An interviewer-administered questionnaire was completed for each consenting woman and inserted into her folder for retrieval and sample collection at delivery. For those presenting for the first time in the labor room in the active phase of labor, cord blood was collected at delivery and adequate information about the study was passed while resting in the postnatal ward. Those who were eligible and consented were enrolled and other aspects of the study completed, otherwise, the cord blood was discarded back into the placenta bag. Information sought through the questionnaire included: Age of the mother, educational attainment and occupation of the mother and father, housing, religious practices, parity, antenatal history of index pregnancy, Gestational age, last childbirth, dietary habit, past medical history suggestive of rickets in the family, HIV status and Drug history. Weight of the newborn was measured using a Bassinet weighing machine with a sensitivity of 50 grams, while the length and head circumference were measured using infantometer and inelastic tape to the nearest centimeter, respectively. The three anthropometric indices were classified into low, normal and high using the nomogram developed by the International Fetal and Newborn Growth Consortium for the 21st Century (INTERGROWTH-21st).[19] Socioeconomic status was determined from parental education and occupations using the model by Oyedeji et al.[20] Venous blood sample (3-5 mls) was collected from the mother with a syringe or from a cannula at the point of delivery into a plain bottle without application of a tourniquet to prevent red cells lysis. Cord blood was obtained from the placenta end immediately after cutting the cord and the blood allowed to drip into the sample bottle. Both blood samples were centrifuged and separated into serum and were stored at -20°C until analysis.
Vitamin D assay
Vitamin D was assayed using Competitive-Enzyme linked Immunosorbent Assay (ELISA) kit manufactured by Elabscience® with the manufacturer stated sensitivity of 1.88 ng/ml and detection range of 3.13-200 ng/ml. The procedure was conducted by two experienced laboratory scientists. The vitamin D levels were measured in ng/ml and were classified using vitamin D status definition as recommended in the recent Global Consensus Recommendations on Prevention and Management of Nutritional Rickets of 2014.[21] Levels >20 ng/ml (50 mmol/L) will be interpreted as vitamin D sufficient, 12-20 ng/ml as insufficient and <12 ng/ml as deficient for both mother and newborn.
Calcium, Phosphorus, Albumin and Alkaline phosphatase assay
Calcium, phosphorous, albumin and alkaline phosphatase were assayed by manual colourimetric method using RANDOX® kits for calcium, phosphorous and albumin, respectively, and QUIMICA CLINICA APLICADA® kit for alkaline phosphatase. The procedure was carried out by the same laboratory scientists at the University of Maiduguri Teaching Hospital chemical pathology Laboratory. In each case, a fixed amount of sample, standard and distilled water in different test tubes were reacted with appropriate test reagent leading to a colour change. The absorbance of the sample and standard was read in a spectrophotometer against the distilled water (reagent blank) at the appropriate wavelength for each analyte. Serum calcium, phosphorous and albumin were calculated using the absorbance of the sample and that of the standard from the equation below as provided by the kit manufacturer:
Alkaline phosphatase on the other hand was calculated from a similar but slightly different formula as provided by the manufacturer:
Total serum calcium level, corrected for albumin, was calculated using calcium calculator[22] which is based on this formula:
The corrected total serum calcium was classified as normal if between 2.05 mmol/l and 2.6 mmol/l, as low if less than 2.05 mmol/l and as high if greater than 2.6 mmo/l for the mothers.[23] In the term neonate, the lower limit of total serum calcium considered as normal was 2.0 mmol/l and 1.75 mmol/l in the preterm neonate.[24]
Similarly, serum phosphate was classified as normal if between 0.9 – 1.49 mmol/l for the mothers and low if less than 0.9 mmo/l and high if greater than 1.49 mmol/l.[23] In the term neonate, phosphate levels between 1.2-2.8 mmol/l were considered normal and 1.7-3.5 mmol/l in the case of preterm.[24]
Serum albumin levels between 23 – 42 g/l, 28 – 43 g/l and 21 – 33 g/l were considered normal for the mother, term infant and preterm, respectively.[23],[24] In the mothers, serum alkaline phosphatase levels of 38-229 u/l were considered normal,[23] while levels of 28-300 u/l and 35 – 604 u/l were considered normal for the term and preterm neonate, respectively.[24]
Statistical analysis
Data obtained were entered and analysed using SPSS version 16.0 (SPSS, Chicago, ILL, USA). Baseline characteristics were presented in a frequency table. Vitamin D, Calcium, Phosphate and alkaline phosphatase levels of both maternal and cord sera were classified into the various status and the mean level determined. Cord-maternal ratio (CMR) was calculated for vitamin D, calcium and phosphate and classified. Association was tested with Chi-Square and Fisher's exact test as appropriate. Pearson correlation was used to test the relationship between maternal levels and cord levels as well as maternal levels and CMR of vitamin D, Calcium and Phosphate. A P value of <0.05 was considered significant.
Results A total of 84 mothers with their live babies were studied. Majority of the mothers 75 (89.3%) were aged between 20 – 40 years (mean ± SD, 27.2 ± 6.0) none of them was older than 40 years. Two-third of the mothers 56 (66.6%) were at least multiparous among whom 48 (85.7%) last delivered more than 2 years ago. Seventy-six (90.5%) of the pregnancies were supervised and 70 (83.3%) used only routine ANC drugs throughout the pregnancy. Eleven (13.1%) of the mothers reported having hypocalcaemic tetany in either previous or index pregnancy.
There were slightly more males 45 (53.6%) than female 39 (46.4%) among the newborn with M : F ratio of 1.15:1. Majority 78 (92.9%) of them were term neonates and had normal birth weight 79 (94.0%). Similarly, 76 (90.5) and 79 (94.0%) had normal birth length and head circumference, respectively [Table 1].
[Table 2] shows the pattern of consumption of vitamin D rich diets and exposure to sunlight among the mothers. More than half of the mothers regularly consumed eggs and dairy product 50 (59.5%), while 43 (51.1%) consumed oily fish regularly. On the pattern of sunlight exposure, slightly more than half 46 (54.8%) of the mothers have occupations that entail outdoor activities and almost similar number 47 (55.9%) spent at least 3 hours under the sun daily on average. Majority of them 70 (83.3%) exposes only their faces and hands while outdoor, while 71 (84.5%) lived in a house with an open courtyard or compound. Only 2 (2.4%) of the women admitted ever intentionally exposing themselves for sunbath and none ever used sunscreen.
Vitamin D, calcium, phosphate and alkaline phosphatase status
Close to half, 40 (47.6%), of the mothers had low serum vitamin D of whom 17 (20.2%) and 23 (27.4%) were deficient and insufficient, respectively. Fifteen (17.9%) of the newborns had insufficient cord vitamin D levels but none of them was deficient. Seventy-three (86.9%) of the newborn-maternal pairs had vitamin D cord maternal ratio (CMR) of ≥1 [mean (SD) CMR was 1.88 (1.38)]. Seven (8.3%) and 3 (3.6%) of the mothers were low in serum calcium and phosphate, respectively, while 19 (22.6%) had high alkaline phosphatase. Again, none of the newborns had low serum calcium, phosphate, or elevated alkaline phosphatase. The CMR were ≥1 in 55 (65.5%) and 81 (96.4%) of the newborn-maternal pairs for calcium [mean (SD) CMR = 1.05 (0.14)] and phosphate [mean (SD) CMR = 1.67 (0.43)], respectively, [Table 3]a and [Table 3]b.
Relationship between maternal and cord vitamin d, calcium and phosphate levels
There was a strong and positive correlation between the maternal and cord blood levels of vitamin D (r = 0.740, P = < 0.001), with a shared variance of 0.548 [Figure 1].
There was no significant correlation between the maternal and cord serum calcium and phosphate levels (r = –0.036, P = 0.747 and shared variance = 0.001) and (r = + 0.187, P = 0.089 and shared variance = 0.035), respectively.
Vitamin D status and associated variables
[Table 4] shows the association of the various variables to maternal serum vitamin D status. Low vitamin D status (deficiency and insufficiency) was proportionately distributed across the maternal age groups, hence there was no significant association between maternal age and serum vitamin D level (P = 0.873). Although mothers who were of the low socioeconomic class had a slightly lower prevalence of vitamin D deficiency 3 (18.8%) and insufficiency 3 (18.8%) when compared to those of high class; 4 (22.2%) and 6 (33.3%), and the middle class 10 (22.0%) and 14 (28.0%) for deficiency and insufficiency, respectively, this was however not statistically significant (P = 0.868). Similarly, parity, time of last childbirth, ANC attendance, and HIV infection all showed no significant association with maternal Serum Vitamin D levels (P > 0.05). History of tetany in the index or previous pregnancies also had no significant effect on maternal vitamin D status.
Table 4: Association of Maternal Serum Vitamin D Status to various factorsThe highest prevalence of vitamin D deficiency 2 (28.6%) and insufficiency 3 (42.9%) were among mothers that consumed eggs weekly while the least prevalence was seen among those who consumed eggs most days 5 (22.7%) and 6 (21.4%) for deficiency and insufficiency, respectively, but this relationship was not statistically significant (P = 0.814). Similarly, the maternal consumption pattern of dairy product and oily fish had no significant effect on the vitamin D status (P > 0.05). Mothers living in a house without a courtyard, with least sunlight exposure and covering the entire body when outdoors had a higher prevalence of Vitamin D deficiency and or insufficiency compared to other groups in their respective cohort, but again these were not statistically significant in all the cohort (P > 0.05).
[Table 5] shows the association between some maternal and newborn factors and cord vitamin D status. The maternal age had no significant effect on cord vitamin D status (P = 0.659). The newborns of primiparous women had slightly higher, though not significant, the prevalence of cord blood vitamin D insufficiency when compared to others (P = 0.366). The highest prevalence of vitamin D insufficiency 2 (40.0%) was seen in the neonates whose mother had antimalarial during pregnancy, while the least prevalence was seen among those who took only ANC routine drugs. However, this association was not significant (P = 0.461). History of tetany, as well as duration of last childbirth all, had no significant effect on cord blood vitamin D status. HIV-exposed infants had higher prevalence of cord blood vitamin D insufficiency than HIV naïve neonates, but this association was not significant (P = 0.216). Male 8 (17.8%) and female 7 (17.9%) neonates had equal prevalence of cord blood vitamin D insufficiency (P = 1.000). The highest prevalence of cord blood vitamin D insufficiency was seen among term neonates 15 (19.2%) with normal birth weight 15 (19.0), however, this was not significant (P > 0.05). Newborn length and head circumference at birth all had no significant association with cord blood vitamin D status of the neonate.
Table 5: Effect of Some Maternal and Neonatal factors on Cord blood Vitamin D Status Discussion The mean (SD) maternal serum vitamin D of 26.16 (16.63) ng/ml observed in this study is higher than previously reported in Iran,[14] China,[13] United Kingdom[25] and Nigeria.[11] The higher maternal serum vitamin D in this study may be due to differences in geographical location between this study and the others.[13],[14],[25] Maiduguri is the closest to the equator of the other locations. It is a known fact that the higher the altitude the less the ultraviolet B rays reaching the earth.[26] The same cannot be said for the lower vitamin D level reported by Sanchez et al.[11] from the same centre as this study. Although the reason for the difference may not be clear, Sanchez et al.[11] studied only 10 newborn-maternal pairs. The observed mean maternal serum vitamin D level is lower than the 37 ng/mL earlier reported by Okonofua et al.[10]from Nigeria. Differences in setting and cultural practices with regards to sunlight exposure between the two studies may explain the difference. While Okonofua et al.[10] studied women in Ife and Benin from Southern Nigeria where women are more likely to engage in longer outdoor activities including farming and are also less likely to cover extensively while outdoor, 63 (75.0%) of the women in this study from Maiduguri North-eastern Nigeria were housewives with much shorter outdoor activities and 73 (86.9%) of them at most exposed the face and hands while outdoor due to religious and cultural practices.
The prevalence of vitamin D deficiency among the mothers in this study despite the abundance of all-year-round sunshine is relatively high. This suggests that certain factors or behavior are greatly impeding efficient utilization of this resource. Consistent with the high mean maternal serum vitamin D observed in this study, the prevalence of vitamin D deficiency is lower than in Iran[14] and China,[13] but similar to the report from the United Kingdom.[25] The finding of vitamin D deficiency in this study is, however, not in agreement with the earlier finding of a complete vitamin D sufficiency by Okonofua et al.[10] among pregnant Nigerian women including purdah-clad ones. The reason for this difference in finding despite being from the same country is not clear but may be due to cultural variation as earlier highlighted.
The effects of several factors on maternal serum vitamin D status in this study were evaluated and similar to our finding, Gale et al.[25] also found no significant relationship between maternal serum vitamin D and maternal age, height, weight, social class, and educational qualifications. In contrast, Fraser et al.[27] found hypovitaminosis D to be significantly associated with low socioeconomic status. The reason for the difference in finding between our work and that of Gale et al.[25] on one side and Fraser et al.[27] on the other is not clear.
Contrary to the well-established effect of sunlight exposure on serum vitamin D status we could not establish a significant association between maternal serum vitamin D status and any of the proxy for sunlight exposure. This finding is probably because none of the variables assessed is an independent predictor of sunlight exposure. For example, a woman that reports spending an average of 3 hours under the sun daily while fully covering the body is unlikely to benefit from the effect of sunlight exposure. This is likely the case in this study where factors predictive of poor sunlight exposure such as the extensive coverage of the body were practiced by 83.3% of the studied population.
The mean (SD) cord serum vitamin D of 38.34 (20.64) ng/ml observed in this study is high and indicates overall sufficient vitamin D status in the neonates. It is higher than 13.2 ± 7.72 reported by Sanchez et al.[11] from Maiduguri, 23 ng/ml reported by Okonofua et al.[10] among newborns of Nigerian women, 16.4 ± 7.56 ng/ml and 6.68 ± 1.16 ng/ml found by Wang et al.[13] and Kazemi et al.[14] from China and Iran, respectively. This higher mean cord serum vitamin D could be attributed to the higher mean maternal serum vitamin D reported in this study when compared to that by Sanchez et al.,[11] Wang et al.[13] and Kazemi et al.[14] The same cannot be said of the lower value reported by Okonofua et al.[10] whose mean maternal serum vitamin D level was much higher than reported in this work. The relationship between maternal and cord serum vitamin D is not completely understood. While this study and previous ones[13],[14],[25] have consistently demonstrated a significant positive correlation (r = 0.740 and P = < 0.001) between maternal and cord serum vitamin D level, the strength and absolute implication of the correlation varies. We found a higher mean cord serum vitamin D compared to the mean maternal serum vitamin D with a mean (SD) CMR of 1.88 (1.38). Wang et al.[13] also found a higher mean cord serum vitamin D level but with a lower mean CMR of 1.14 (0.96). Others[11],[13],[14] however, have found higher mean maternal serum vitamin D with mean CMR of <1. The reason for this variation in the relationship between the maternal and cord vitamin D level is not clear but may indicate variation in the efficiency of transplacental transfer of vitamin D which may be dependent on other variables. Gale et al.[25] however, found maternal serum level of vitamin D to be the major determinant of the strength of correlation and maternal serum vitamin D levels of 20 ng/ml and below were associated with poor or no correlation.
In this study, we explored the effect of several factors on cord serum vitamin D and none had a significant effect on cord serum vitamin D. In contrast, Zhu et al.[28] found a significant association between birth weight and cord serum vitamin D levels and concluded that lower cord vitamin D level was associated with small for gestational age (SGA). But in similarity to our finding, they found no significant association between cord serum vitamin D level and maternal age, infant gender, parity, and maternal socioeconomic status. In another study, Naik et al.[29] found significantly higher cord vitamin D level among primiparous mothers and mothers with gestational diabetes, but no significant difference in cord serum vitamin D between SGA and AGA, purdah clad mothers, and non-purdah clad mothers and male and female was demonstrated. The reason for this variation in findings is not clear but may be due to the difference in classification of vitamin D status. While these factors were compared among the sufficient, insufficient, and deficient groups in our study, Zhu et al.[30] classified the cord vitamin D into ten deciles and found a U-shaped relationship.
The prevalence of hypocalcemia among mothers was 8.3%. This is quite low considering the reports of earlier studies.[30],[31] This low prevalence observed in this study may be due to the corresponding low prevalence of vitamin D deficiency among these mothers. Besides, over 90% of these mothers had supervised pregnancy and were on daily routine ANC drugs which included calcium lactate. Furthermore, approximately 60% of them reported consuming the dairy product for most days of the week. All the neonates had a normal level of cord calcium, phosphate, and alkaline phosphatase. The mean cord serum calcium and phosphate were higher than that observed in the maternal serum with mean CMR of >1. This is in keeping with the established pattern[32] and findings from previous studies.[11],[33] Calcium and phosphate are known to be actively transferred through the placenta under the effect of PTHrP irrespective of the calcium and phosphate status of the mother. The mean maternal alkaline phosphatase was much higher than that of the neonate due to high bone turnover rate in pregnancy.
Conclusion Vitamin D deficiency and insufficiency is high among pregnant women in Maiduguri, while insufficiency is a common occurrence among the newborns. Maternal vitamin D level is an important determinant of fetal status, although other factors may play a role in the dynamics of transplacental transfer. Hypocalcemia is uncommon among newborns and low among booked pregnant women taking routine antenatal drugs in Maiduguri. We, therefore, recommend routine Vitamin D supplementation to all pregnant women and newborns.
Limitations
The result of this study is limited by the method of vitamin D assay employed (EIA) which has a high potential of cross-reactivity with other metabolites of vitamin D particularly in infants in whom the level of C-3 epimer of 25OHD is relatively high.
Acknowledgements
We wish to acknowledge the staff and resident doctors posted to the labor ward during the period of the research for their immense support in sample collection.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
The research was conducted in partial fulfilment for the award of fellowship in Paediatric Endocrinology of the Paediatric Endocrinology Training Centre for West Africa, Lagos. The fellowship was supported by the European Society of Paediatric Endocrinology (ESPE) and ISPAD. A grant of €1000.00 was provided by the ESPE for this research.
Conflicts of interest
There are no conflicts of interest.
References 
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