Do maternal haemodynamics have a causal influence on treatment for gestational diabetes?

Figures & data

Figure 1. Flow chart demonstrating inclusion and exclusion of recruited participants.

Table 1. Baseline demographic details, maternal haemodynamics, and pregnancy outcomes of the study groups. Data presented as mean + standard deviation or n (percentage).

	Dietary management (n = 62)	Pharmacological treatment (n = 58)	p Value
Maternal age (years)	31 ± 5.3	32 ± 5.2	0.627
Maternal height (cm)	161 ± 5.0	162 ± 7.6	0.511
Maternal weight at booking (kg)	70 ± 16.5	80 ± 21.0	0.004
Maternal body mass index at booking (kg/m^2)	27 ± 5.8	30 ± 6.7	0.003
Parity (n)			0.718
Nulliparous	26 (41.9)	25 (43.1)
Multiparous	36 (58.1)	33 (56.9)
Maternal ethnicity (n)			0.706
White British/ European	31 (50.0)	27 (46.6)
Non White	31 (50.0)	31 (53.4)
African/ Afro-Caribbean	2 (3.2)	11 (19.0)
South Asian	21 (33.9)	14 (24.1)
Other	8 (12.9)	6 (10.3)
Diagnostic Factors
Gestational age at diagnosis (days)	180 ± 27.2	185 ± 26.8	0.396
OGTT Fasting glucose (mmol/L)	4.5 ± 0.83	5.0 ± 0.83	<0.001
OGTT 2 hour glucose (mmol/L)	8.3 ± 1.05	8.5 ± 1.47	0.070
Maternal haemodynamic assessment
Gestational age at assessment (days)	206 ± 16.9	201 ± 22.2	0.225
Diet treatment duration prior to assessment (days)	22.5 ± 13.6	19 ± 14.4	0.165
Interval from assessment to initiation of pharmacological treatment	n/a	17.7 ± 15.69	n/a
Cardiac Output (L/min)	7.1 ± 1.48	7.4 ± 1.28	0.215
Stroke Volume (mls)	79.5 ± 17.2	79.5 ± 13.84	0.989
Heart Rate (bpm)	87.6 ± 11.70	92.9 ± 11.90	0.014
Total Peripheral Resistance (dynes x s/cm2)	1048.6 ± 265.93	1004.9 ± 159.28	0.302
Mean arterial blood pressure (mmHg)	80.5 ± 10.20	82.3 ± 11.97	0.378
Brachial Augmentation Index (%)	−58.7 ± 15.42	−56.2 ± 16.82	0.405
Aortic Augmentation Index (%)	7.6 ± 7.82	9.2 ± 8.55	0.310
Aortic Pulse Wave Velocity (m/s)	7.8 ± 1.04	8.4 ± 1.61	0.029
Pregnancy Outcomes
Gestation at delivery	273.1 ± 8.90	271.7 ± 5.26	0.310
Birth weight (g)	3203 ± 460.1	3432 ± 488.4	0.009
Birth weight centile	42 ± 30.5	60 ± 29.8	0.001
Birth weight category (n)			0.045
Small for gestational age	12 (19.4)	5 (8.6)
Large for gestational age	4 (6.5)	11 (19.0)
Hypertensive Disorder of Pregnancy (n)	4 (6.5)	1 (1.7)	0.195

Figure 2. Causal directed acyclic graph (DAG). A directed acyclic graph (DAG) representing the causal relationships amongst demographics, haemodynamic variables, need for pharmacological treatment of GDM. Boxes represent variables of interest (nodes) and arrows (edges) represent the direction of known relationships between these variables. The dotted lines represent relationships we wanted to investigate.

Table 2. Effect of maternal characteristics, diagnostic factors, and haemodynamic variables on need for pharmacological management. Logistic regression coefficients were converted into the odds ratio using the following equation: (Odds Ratio = e^{logistic regression coefficient}) to quantify the effect size.

Variable	Effect	Logistic Regression Effect Coefficient (95% CI)	Odds Ratio (95%CI)
Mean Arterial Pressure (White)	Total	0.010 (−0.036−0.056)	1.01 (0.965−1.058)
Mean Arterial Pressure (Non-white)	Total	−0.026 (−0.077−0.024)	0.97 (0.926−1.024)
Mean Arterial Pressure (White)	Direct	0.034 (−0.066−0.133)	1.03 (0.936−1.142)
Mean Arterial Pressure (Non-white)	Direct	−0.005 (−0.077−0.066)	1.00 (0.926−1.068)
History of GDM	Total	0 (−1.240−1.240)	1.00 (0.289−3.455)
Total Peripheral Resistance	Total	−0.001 (−0.005−0.002)	1.00 (0.995−1.002)
Cardiac Output	Total	−0.166 (−0.936−0.604)	0.85 (0.392−1.829)
Cardiac Output	Direct	−0.445 (−1.350−0.460)	0.64 (0.259−1.584)
Aortic Augmentation Index	Total	0.036 (−0.016−0.088)	1.04 (0.984−1.092)
Brachial Augmentation Index	Total	0.021 (−0.006−0.047)	1.02 (0.994−1.048)
Aortic Pulse Wave Velocity	Total	0.183 (−0.189−0.555)	1.20 (0.828−1.742)
OGTT: Fasting Blood Glucose	Total	3.652 (−143.456−150.760)	38.54 (5.062 × 10^−63 − 2.934 × 10^65
OGTT: 2 hr Blood Glucose	Total	−8.823 (−46.371−28.724)	0.0001 (7.302 × 10^−21 − 2.974 × 10^12)
Gestation at diagnosis	Total	−0.001 (−0.003−0.001)	1.00 (0.997−1.001)
Maternal Booking BMI	Total	0.053 (−0.120−0.227)	1.05 (0.887−1.255)
Maternal Booking BMI (White)	Direct	0.091 (−0.448−0.258)	1.10 (0.639−1.294)
Maternal Booking BMI (Non-white)	Direct	0.181 (0.032−0.330)	1.20 (1.033−1.391)

GDM: gestational diabetes; OGTT: oral glucose tolerance test; BMI: body mass index.

Table 3. Effect of maternal characteristics, diagnostic factors, and haemodynamic variables on need for pharmacological management (based on secondary analysis DAG shown in Figure S1) Logistic regression coefficients were converted into the odds ratio using the following equation: (Odds Ratio = e^{logistic regression coefficient}) to quantify the effect size.

Variable	Effect	Logistic Regression Effect Coefficient (95% CI)	Odds Ratio (95% CI)
Mean Arterial Pressure (White)	Total	0.010 (−0.036−0.056)	1.01 (0.965−1.058)
Mean Arterial Pressure (Non-white)	Total	−0.026 (−0.077−0.024)	0.97 (0.926−1.024)
Mean Arterial Pressure (White)	Direct	0.031 (−0.068−0.129)	1.03 (0.934−1.138)
Mean Arterial Pressure (Non-white)	Direct	−0.006 (−0.076−0.065)	0.99 (0.927−1.067)
Total Peripheral Resistance	Total	−0.002 (−0.005−0.001)	1.00 (0.995−1.001)
Cardiac Output	Total	−0.183 (−0.577−0.211)	0.83 (0.562−1.235)
Cardiac Output	Direct	−0.420 (−0.944−0.105)	0.66 (0.389−1.111)
Aortic Augmentation Index	Total	0.036 (−0.016−0.088)	1.04 (0.984−1.092)
Brachial Augmentation Index	Total	0.021 (−0.006−0.047)	1.02 (0.994−1.048)
Aortic Pulse Wave Velocity	Total	0.183 (−0.189−0.555)	1.20 (0.828−1.742)
OGTT: Fasting Blood Glucose	Total	3.652 (−143.456−150.760)	38.54 (5.062 × 10^−63−2.934 × 10^65
OGTT: 2 hr Blood Glucose	Total	−8.823 (−46.371−28.724)	0.0001 (7.302 × 10^−21 − 2.974 × 10^12)
Maternal Booking BMI	Total	0.053 (−0.120−0.227)	1.05 (0.887−1.255)
Maternal Booking BMI	Direct	0.111 (0.019−0.202)	1.12 (1.019−1.224)

OGTT: oral glucose tolerance test; BMI: body mass index.

Data availability statement

The data that support the findings of this study are available from the corresponding author, [AA], upon reasonable request.