System Identification, State Estimation, And Control Approaches to Gestational Weight Gain Interventions

abstract: Excessive weight gain during pregnancy is a significant public health concern and has been the recent focus of novel, control systems-based interventions. Healthy Mom Zone (HMZ) is an intervention study that aims to develop and validate an individually tailored and intensively adaptive intervention to manage weight gain for overweight or obese pregnant women using control engineering approaches. Motivated by the needs of the HMZ, this dissertation presents how to use system identification and state estimation techniques to assist in dynamical systems modeling and further enhance the performance of the closed-loop control system for interventions. Underreporting of energy intake (EI) has been found to be an important consideration that interferes with accurate weight control assessment and the effective use of energy balance (EB) models in an intervention setting. To better understand underreporting, a variety of estimation approaches are developed; these include back-calculating energy intake from a closed-form of the EB model, a Kalman-filter based algorithm for recursive estimation from randomly intermittent measurements in real time, and two semi-physical identification approaches that can parameterize the extent of systematic underreporting with global/local modeling techniques. Each approach is analyzed with intervention participant data and demonstrates potential of promoting the success of weight control. In addition, substantial efforts have been devoted to develop participant-validated models and incorporate into the Hybrid Model Predictive Control (HMPC) framework for closed-loop interventions. System identification analyses from Phase I led to modifications of the measurement protocols for Phase II, from which longer and more informative data sets were collected. Participant-validated models obtained from Phase II data significantly increase predictive ability for individual behaviors and provide reliable open-loop dynamic information for HMPC implementation. The HMPC algorithm that assigns optimized dosages in response to participant real time intervention outcomes relies on a Mixed Logical Dynamical framework which can address the categorical nature of dosage components, and translates sequential decision rules and other clinical considerations into mixed-integer linear constraints. The performance of the HMPC decision algorithm was tested with participant-validated models, with the results indicating that HMPC is superior to "IF-THEN" decision rules.Dissertation/ThesisDoctoral Dissertation Chemical Engineering 201

An Investigation into the Dietary and Health Behaviours of Pregnant Women in Ireland

Maternal obesity increases the risk of metabolic complications in pregnancy such as gestational diabetes mellitus (GDM). Effective weight management following childbirth may reduce long-term metabolic risks among women of child bearing age. The aim of this study was to investigate the diet and health behaviours of pregnant and postpartum women in Ireland. Accurate dietary assessment in pregnancy is often difficult to achieve. We have shown that dietary under-reporting is more likely among pregnant women who are younger, materially deprived, obese and who have increased adiposity. These findings suggest that dietary underreporting represents a source of potential bias in obstetric obesity research. Obese pregnant women of low socioeconomic status may require more specialised dietary assessment methods. Technology increasingly dictates the way in which we collect and communicate information, highlighting the potential utility of innovative web-based dietary assessment and intervention tools. We compared dietary quality scores from a newly developed online Dietary Assessment Tool against nutrient intakes derived using the recently validated Willett Food Frequency Questionnaire. The relatively good agreement between these two dietary assessment methods suggests that our food-based dietary quality scores are reflective of important nutrient intakes in pregnancy. Nutritional manipulation based on dietary intervention does not appear to prevent GDM. Neither food group nor macronutrient intakes in the periconceptional period were associated with fasting plasma glucose (FPG) levels in our cohort of pregnant women. Obesity in early pregnancy was the main predictor of elevated FPG levels, highlighting the potential value of preconceptional weight management interventions in preventing GDM. There is a paucity of data describing maternal weight changes in the postpartum period. We found that maternal weight and body composition trajectories after pregnancy were not linear, and that they differed between women who were obese and those who were not obese in the first trimester. The role of breastfeeding in postpartum weight change is not clear. We found that postpartum changes in maternal weight and percentage body fat were not associated with infant feeding method after adjusting for important confounders such as diet and exercise. Overall, my findings commend the pre-conceptional period as an important window of opportunity in the prevention of GDM and postpartum obesity

The contribution of intra-organ fat deposition to insulin resistance in normal pregnancy and gestational diabetes

MD ThesisGestational diabetes (GDM) affects 3-5% of pregnancies and is associated with stillbirth, accelerated fetal growth and fetal growth restriction, birth trauma, increased risk of caesarean section and third degree tear. Many mothers with GDM go on to develop type 2 diabetes (T2DM) in later life. T2DM is associated with increased fat deposition in the muscle, liver and pancreas leading to insulin resistance, impaired insulin secretion and hyperglycaemia. Muscle insulin resistance and its association with raised intramyocellular lipid is one of the first detectable changes in T2DM. Low calorie dieting causes reversal of T2DM and removal of intra-organ fat. The pathophysiology of GDM is poorly understood, but fat deposition may play a similarly important role. Low calorie dieting is poorly studied and viewed with caution in pregnancy. This work explores the nature of physiological insulin resistance in pregnancy and the clinical and metabolic outcomes of reducing calorie intake to 1,200kcal/day in pregnancy affected by GDM (WELLBABE – WEight Loss Looking for Babe and mother BEtter outcomes study). The LIPIDPREG study used magnetic resonance spectroscopy (MRS), a non-invasive technique that has not been previously used in pregnancy, to quantify intramyocellular lipid within the soleus muscle in women with normal glucose tolerance. A standardised meal test was used to calculate insulin sensitivity and secretion. Studies were done at 34 weeks gestation and 12 weeks postpartum. Eleven primiparous healthy pregnant women (age: 27-39 years, body mass index 24.0±3.1 kg/m2) and no personal or family history of diabetes underwent magnetic resonance studies to quantify intramyocellular lipid, plasma lipid fractions, and insulin sensitivity. The meal-related insulin sensitivity index was considerably lower in pregnancy (45.6±9.9 vs. 193.0±26.1; 10-4 dl/kg/min per pmol/l, p=0.0002). Fasting plasma triglyceride levels were elevated 3-fold during pregnancy (2.3±0.2 vs. 0.8±0.1 mmol/l, p<0.01) and the low-density density lipoprotein fraction, responsible for fatty acid delivery to muscle and other tissues, was 6-fold elevated (0.75±0.43 vs. 0.12±0.09 mmol/l; p=0.001). However, mean intramyocellular lipid concentrations of the soleus muscle were not different during pregnancy (20.0±2.3 vs. 19.1±3.2 mmol/l, p=0.64). In conclusion, the pregnancy effect on muscle insulin resistance is distinct from that underlying type 2 diabetes. The WELLBABE study recruited women with an abnormal oral glucose tolerance test from 21 to 34 weeks (mean 27 weeks) gestation. MRS quantification of liver fat, a standardised meal test and plasma lipid profiles were performed before and after a 1,200kcal/day diet. Participants food diary and glycaemic control were reviewed on a daily basis for 4 weeks, iv through the use of smartphone technology. Fourteen women, who completed the study, achieved a weight loss of 1.6±1.7 kg over the 4 week dietary period. Mean weight change was -0.4 kg/week in the study group vs +0.3 kg/week in the comparator group (p=0.002). Liver triacylglycerol level was normal but decreased following diet (3.7% [interquartile range, IQR 1.2-6.1%] vs 1.8% [IQR 0.7-3.1%], p=0.004). There was no change in insulin sensitivity or production. Insulin was required in six comparator women vs none in the study group (eight vs two required metformin). Blood glucose control was similar for both groups. The hypo-energetic diet was well accepted. Liver triacylglycerol in women with GDM was not elevated, unlike observations in non-pregnant women with a history of GDM. A 4 week hypo-energetic diet resulted in weight loss, reduced liver triacylglycerol and minimised pharmacotherapy. The underlying pathophysiology of glucose metabolism appeared unchanged. The results of these two studies are presented in this thesis and from this work a hypothetical model of insulin resistance in pregnancy and GDM is presented. It is demonstrated that reduced calorie dietary intervention is both acceptable and feasible in pregnancy and reduced the need for medication in women with GDM. Further studies are needed in this area to unravel the true pathophysiology of GDM and to develop a reduced calorie dietary intervention that could be used in routine clinical practice.Wellbeing of Women and the North East Diabetes Trust

Lifestyle behaviours and beliefs of pregnant women with gestational diabetes: a longitudinal follow-up study

Women with gestational diabetes mellitus (GDM) have increased risk of adverse pregnancy outcomes such as delivering Large-for-gestational-age babies, preeclampsia or birth trauma, as well as increased risk of developing type 2 diabetes (T2DM) later in life. Lifestyle management through a healthy diet and physical activity both during and after a GDM pregnancy is the first line treatment option in GDM management and for delaying the onset of T2DM. The research for this Master thesis had two main aims: firstly, to investigate the dietary intake and beliefs related to dietary intake of pregnant women with GDM in Cape Town, and whether they adhere to established dietary recommendations and secondly, to investigate the change in dietary intake, physical activity and associated factors as well as beliefs related to these lifestyle behaviours in women with GDM from pregnancy to a postpartum follow-up assessment. Methods: For the first aim a cross-sectional study was conducted on 239 pregnant women with GDM in Cape Town and for the second aim, 98 women were followed-up 3 to 15 months postpartum. Assessments included: a quantified Food Frequency Questionnaire (qFFQ), General Practice Physical Activity Questionnaire (GPPAQ) and beliefs relating to specific dietary components were assessed using the Theory of Planned Behaviour (TPB). Results: At baseline, the majority of the sample had inadequate intakes of vitamin D (87.4%), folate (96.5%) and iron (91.3%), and the dietary intake of these women was not optimal and fell short in meeting several nutritional guidelines for pregnant women with hyperglycaemia. At follow-up, the dietary changes made during pregnancy were not maintained postpartum. Fruit and vegetable intake (F&V) fell short of the recommended 400g intake at both baseline and follow-up. The intake of carbohydrates, added sugar, table sugar, sugar sweetened beverages (SSBs), pulses and energy-dense foods increased significantly from pregnancy to postpartum. In conclusion, women with prior GDM fail to maintain the dietary changes made during pregnancy. These women being at risk for the development of T2DM would benefit from interventions supporting behaviour change towards a healthier lifestyle in pregnancy and continued in the postpartum period

Gestational Diabetes Mellitus in Ghana: Validity of Screening Tests, Prevalence, Maternal Risk Factors and Pregnancy Outcomes

Background: Gestational diabetes is increasing globally. Studies from Sub-Saharan Africa have investigated the risk factors but reported prevalence is often based on one diagnostic test while short-term outcomes have scarcely been explored. In primary settings, gestational diabetes is tested after screen-positive glycosuria and/or presence of clinical risk factors. There is suspicion of missing cases due to likelihood of active hyperglycemia without detectable glycosuria and the wide profile of risk facts associated with gestational diabetes. Despite recent updates of diagnostic guidelines with lowered diagnostic cut-off in most cases, opinions are divided on the screening methods diagnostic cut-offs to apply, and whether to do selective screening followed by diagnostic testing of screen-positive cases vis-à-vis universal testing of all pregnant women. Objective: This study was conducted to address three overarching objectives: (1) validate the diagnostic validity of screening tests for gestational diabetes and estimate the proportion of cases that could be missed if selective screening is applied; (2) estimate the prevalence of gestational diabetes and assess the risk factors; and (3) assess the pregnancy outcomes including the extent of attainment of euglycemia at 12 weeks postpartum. Materials and methods: This study employed blind-comparison-to-the-gold-standard and case-control designs embedded in a prospective cohort study. Singleton non-diabetic singleton pregnant women (n=807) were recruited in the first trimester from five state-owned hospitals serving rural and peri-urban communities in Ghana. They were all screened for gestational diabetes from 13-20 weeks using dipstick glycosuria, random glucose and clinical risk factor assessment. Between 20-34 weeks, 491 pregnant women were tested for gestational diabetes using glycated hemoglobin, fasting glucose, 1-hour and the ‘gold standard’ 2-hour oral glucose tolerance test following the universal ‘one-step’ approach. Dietary and obstetric history were assessed retrospectively while physiologic measurements were repeated throughout pregnancy. Case definition was fasting ≥5.6 mmol/L and/or 2-hour postprandial glucose ≥8.5 mmol/L. Short-term outcomes of 403 and 100 women were traced at delivery and 12 weeks postpartum respectively. Validity of test instruments were estimated using standard disease measures. Adjusted odds ratio for gestational diabetes and relative risk for adverse birth outcomes were estimated by logistic regressions. Results: Fasting plasma glucose had the highest diagnostic validity among all the screening and diagnostic tests evaluated. Fasting glucose cut-off ≥5.1 mmol/L threshold had the highest clinically relevant sensitivity and specificity but the ≥5.6 mmol/L threshold had higher disease prediction. Selective screening using glycosuria, random glucose and risk factors missed 97.4%, 87.2% and 45.7% of cases respectively. Using the area under the curve to determine the diagnostic accuracy and test performance, fasting and 1-hour postprandial glucose tests were found to be very good, random glucose was poor whereas glycated hemoglobin was not diagnostically useful. Depending on the diagnostic test and cut-off used, 5-27% of participants were diagnosed with gestational diabetes. Overall 15.9% met the case definition; prevalence per 2-hour postprandial glucose ≥8.5 mmol/L was 9.0% and per fasting glucose ≥5.6 mmol/L was 10.8%; 3.9% were positive in both tests. Adjusted risk factors for gestational diabetes included high glycemic intake, obesity, previous Cesarean section and antenatal care in a primary facility. In terms of outcomes, a unit rise in blood glucose significantly increased maternal blood loss and fetal birthweight. Associated adverse birth outcomes were perineal tear and birth asphyxia. At 12 weeks postpartum, 30% of the diagnosed women did not achieve euglycemia. Conclusions and recommendations: Findings show rising gestational diabetes in the general population. Selective screening using glycosuria, random glucose and clinical risk factors are unnecessary due to their low diagnostic validity. Fasting glucose monitoring need to be integrated into all gestational diabetes detection protocols. Cut-off ≥5.1 mmol/L could be applicable for screening at the population level but to make therapeutic decision, cut-off ≥5.6 mmol/L is recommended where 2-hour oral glucose tolerance test is unavailable. Primary facilities need strengthening to test and refer cases. Diet and adiposity are key risk factors that necessitate lifestyle modifications with focus on nutrition education and weight control. Fetuses exposed to hyperglycemia uterine environment require quality obstetric care as birth asphyxia which is a key outcome is likely to compromise their survival. Follow-up on women diagnosed with gestational diabetes is crucial to avert transition into active diabetes. Cut-off values that would balance risks and benefits of adverse pregnancy and long-term outcomes is needed for the Ghanaian population. Physiologic interactions between fasting and oral glucose tolerance tests need further research. ZUSAMMENFASSUNG Hintergrund: Gestationsdiabetes steigt weltweit an. Studien aus Subsahara-Afrika untersuchen die Risikofaktoren; es gibt aber wenig Studien zur Prävalenz und diese basieren oft nur auf einem einzigen diagnostischen Test. Es gibt auch kaum Studien zur Nachverfolgung post partum. In primären Gesundheitseinrichtungen in Ghana beruht die Diagnose Gestationsdiabetes auf einem positiven Glykosurie-Test oder dem Vorhandensein klinischer Risikofaktoren. Vermutlich werden aber viele Fälle übersehen, bei denen eine aktive Hyperglykämie ohne feststellbare Glykosurie besteht. Trotz kürzlich angepasster internationaler Richtlinien für das Screening und die Diagnostik, mit in den meisten Fällen gesenkten Grenzwerten, sind die Meinungen bezüglich der Screening-Möglichkeiten nach wie vor gespalten zwischen einem universellen Screening aller schwangeren Frauen und einem selektiven Screening nach Risikobelastung. Darüber hinaus gibt es unterschiedliche Vorschläge für diagnostische Tests und deren Grenzwerte. Zielsetzung: Diese Studie wurde durchgeführt, um die folgenden drei Ziele zu erreichen: (1) die Validität von Tests zum Screening und zur Diagnose von Gestationsdiabetes in Ghana zu ermitteln, sowie den Anteil von Fällen einzuschätzen, die bei selektivem Screening übersehen werden; (2) (2) die Prävalenz von Gestationsdiabetes in Ghana zu ermitteln, sowie Risikofaktoren zu identifizieren und (3) (3) die kindlichen und mütterlichen Schwangerschaftsergebnisse, einschließlich der mütterlichen glykämischen Situation 12 Wochen postpartum zu untersuchen. Material und Methoden: Die vorliegende Studie ist eine Kohortenstudie mit eingebetteter Fall-Kontroll-Studie die Schwangere während der Schwangerschaft und bis zu 12 Wochen post partum einschließt. Nicht-diabetische Frauen mit einer Einlings-Schwangerschaft (n=807) wurden in ihrem ersten Trimester in fünf staatlichen Krankenhäusern, welche ländliche und halb-städtische Gemeinden in Ghana versorgen, rekrutiert. Sie wurden alle zwischen der 13. und 20. Schwangerschaftswoche auf Gestationsdiabetes untersucht, und zwar mittels Tests auf Glucosurie und Blutzucker. Ebenso wurde ein klinisches Risikoassessment gemacht. Zwischen der 20. und 34. Schwangerschaftswoche, wurden 491 schwangere Frauen nach dem „single-step“ Verfahren untersucht. Dabei wurden glykosyliertes Hämoglobin, Nüchtern-Blutzucker, oraler Glukosebelastungstest 1-Stunden-Wert und als „Goldstandard“ der 2-Stunden-Wert erhoben. Ernährungs- und geburtshilfliche Anamnesen wurden retrospektiv erhoben und bewertet. Die Falldefinition für Gestationsdiabetes lautete: Nüchtern-Blutzucker ≥ 5,6 mmol/L und/ oder 2-Stunden Wert nach oralem Glukosebelastungstest ≥ 8,5 mmol/L. Von 403 Frauen wurden die Geburtsergebnisse erfasst; 100 Frauen aus dieser Gruppe wurden zusätzlich nach 12 Wochen postpartum untersucht. Die adjustierten Odds Ratios für Gestationsdiabetes und für weitere Schwangerschaftskomplikationen wurden mittels logistischen Regression ermittelt. Ergebnisse: Nüchtern-Blutzucker im Plasma hatte die höchste diagnostische Validität von allen getesteten Screening- und Diagnostik-Tests. Nüchtern-Blutzucker-Grenzwerte von ≥5,1 mmol/L hatte die höchste klinisch relevante Spezifität, aber der Schwellenwert ≥5,6 mmol/L hatte einen höheren Krankheitsvorhersagewert. Selektive Screenings, welche mit Testen von Glykosurie, spontanen Blutzuckermessungen und Risikoprofilen durchgeführt wurden, verfehlten 97,4%, 87,2% beziehungsweise 45,7% der Fälle. Benutzt man die „area under the curve“, um die diagnostische Genauigkeit und die Leistung eines Tests zu bestimmen, ergaben der Nüchtern-Blutzucker und der 1-Stunde-Wert des Glukosebelastungstests die besten Ergebnisse. Spontane Blutzuckermessungen hingegen schnitten schlecht ab, während das glykolisierte Hämoglobin diagnostisch nicht brauchbar war. Abhängig davon, welcher diagnostische Test und welcher Grenzwert verwendet wurde, ergaben sich Prävalenzen von 5-27%. Unter Verwendung des eingangs genannten Goldstandards für diese Studie (Nüchtern-Blutzucker ≥ 5,6 mmol/L und/ oder 2-Stunden Wert nach oralem Glukosebelastungstest ≥ 8,5 mmol/L) ergab sich eine Prävalenz für Gestationsdiabetes von 15,9%: Die Prävalenz für den 2-Stundenwert des Glukosebelastungstests von ≥8,5 mmol/L war 9,0% und für den Nüchtern-Blutzucker ≥5,6 mmol/L war 10,8%; bei 3,9 % waren beide Tests positive. Die Risikofaktoren für Gestationsdiabetes beinhalteten großen Zuckerkonsum, Adipositas und vorhergehenden Sectio caesarea. Ein Anstieg der Glukose im Blut um eine Einheit hatte einen signifikanten Anstieg des mütterlichen Blutverlusts sowie des Geburtsgewichts des Neugeborenen zur Folge. Assoziierte ungünstige Geburtenergebnisse beinhalteten perineale Geburtsverletzungen und kindliche Asphyxie. Zwölf Wochen post partum hatten 30% der Frauen mit Gestationsdiabetes noch keine Euglykämie erreicht. Schlussfolgerung und Empfehlungen: Die Ergebnisse zeigen, dass die Prävalenz des Gestationsdiabetes in der Ghana zunimmt. Selektive Screening-Verfahren wie Glykosurie und spontane Blutzuckermessung sind wenig valide und unnötig. Die Nüchtern-Blutzucker-Überwachung sollte jedoch routinemäßig in die Schwangerenvorsorge integriert werden. Die Nüchtern-Blutzucker-Obergrenze von ≥5,1 mmol/L sollte in Ghana für Screenings der aller Schwangeren benutzt werden, um jedoch therapeutische Entscheidungen zu treffen, soll ein diagnostischer Grenzwert von ≥5,6 mmol/L gelten, falls kein oraler Glukosetoleranztest durchführbar ist. Primäre Gesundheitseinrichtungen sollten beim Screening und in der Überweisung von Gestationsdiabetes-Fällen unterstützt werden. Diabetogene Ernährung und Adipositas sind Hauptrisiken, welche eine Änderung des Lebensstils benötigen. Der Fokus der Beratung sollte in der Ernährung und der Gewichtskontrolle liegen. Feten welche intrauterinen Hyperglykämien ausgesetzt waren, brauchen eine spezialisierte Geburtshilfe, da Geburts-Asphyxien eine häufige Folge von Gestationsdiabetes sind und diese das Sterberisiko erhöhen. Es ist wichtig, Frauen mit Gestationsdiabetes nachzubetreuen, um zu verhindern bzw. zu erkennen, ob ein Gestationsdiabetes in einen manifesten Diabetes mellitus übergeht. Die spezifische klinische Wertigkeit von erhöhtem Nüchternblutzucker und pathologischem oralem Glukosetoleranztest im Kontext der Situation in Ghana sollte weiter untersucht werden

Provider and participant views and experiences of the ESTEEM dietary intervention for pregnant women with metabolic risk factors: a qualitative study

Background ESTEEM (Effect of Simple, Targeted diEt in prEgnant women with Metabolic risk factors on pregnancy outcomes), was a randomised controlled trial of a dietary intervention based on the Mediterranean diet. Intervention programmes like this are recognised in the literature as complex to evaluate and engagement and adherence are problematic. There is a need for dietary interventions in pregnancy which are simple and effective. The aim The aim of this study was to explore the views and experiences of the ESTEEM dietary intervention in a pregnant cohort with metabolic risk factors. Methods Qualitative methods using interviews with women, partners (separately) and focus groups with health care professionals were carried out. Data were analysed using thematic analysis. The findings Women were able to plan and adapt their food and use the ESTEEM diet to their own and their family’s advantage. Conversely, some of the information provided during the ESTEEM intervention made women more aware of their metabolic risk factors and more anxious. Women found solutions to their individual concerns during the ESTEEM intervention, by sharing information and ideas, and by supporting each other. Partners perceived the dietary intervention as having benefits for themselves, the mother as well as their children. Men appeared to hold mothers to be mainly responsible for feeding the children and ensuring that what they ate was healthy. Health care professionals considered that developing and maintaining good relationships with women, and skilful and flexible approaches to enable dietary change were needed. They also emphasised the need to include family and friends, and in particular, children in interventions. Conclusions In order to effect dietary change, the material context in which people live must be taken into consideration. Diet and lifestyle interventions will become truly effective if they are codesigned with women and families and health care is co-produced with people

Interventions used by health care professionals to transition preterm infants and neonates from enteral feeds to full-oral feeds: A Scoping review

Background: Preterm infants and neonates may present with dysphagia due to immaturity or the presence of medical conditions. Enteral feeds are used to ensure optimal nutrition is achieved while the neonates are developing appropriate oral feeding skills. Varied interventions may be used to transition neonates to full oral feeds as oral feeding is often a prerequisite for discharge from hospital. Aims: The main aim of this study was to summarize, interpret and analyse the literature on the different interventions used for the transition to full oral feeds in preterm infants and neonates to identify research gaps and to inform clinical practice on the best intervention options. A secondary aim was to validate the findings of the scoping review for the South African context. Methods: A scoping review was conducted. Relevant studies were identified by searching six databases, Google and Google scholar. Inclusion criteria included studies written in English, peer reviewed and published between 1998–2018, that described the interventions used to transition preterm infants and neonates to full oral feeds. Data were extracted from the articles using a data charting form and analysed descriptively and thematically. The findings were shared with health care professionals who work with premature infants and neonates who then participated in a semi-structured interview to provide feedback relevant to the South African context. Results: Forty-seven articles were included. Six broad intervention categories were identified: oral-motor, oral-sensory, other senses, timing, cue-based and utensils. Non-nutritive sucking (NNS) interventions were reported most frequently across single and combined interventions. Outcome measures reported included: time taken to full oral feeds, earlier hospital discharge, long-term feeding outcomes, weight and sucking proficiency. Improved outcomes were associated with NNS and NNS with oral stimulation. Nine health care professionals were interviewed. They confirmed using a number of the interventions, with NNS reported the most. Health care professionals also provided insight into the challenges of implementing some interventions due to limited resources and staffing in the South African context. Conclusions: There are a range of interventions reported in the literature and many of them are used in South Africa. Positive outcomes such as earlier transition to full oral feeds; earlier hospital discharge; improved weight gain and improved sucking proficiency have been reported with NNS and combined NNS and Oral Stimulation interventions, however further studies are needed