Introduction
Pregnancy is an altered physiologic state of an individual. Maternal physiological changes are the normal adaptations that a woman undergoes during pregnancy to accommodate the embryo or foetus. The awareness about various physiological respiratory changes in each trimester helps us to avert complications. The body must change its physiological and homeostatic mechanisms in pregnancy to e nsure the requirement of the foetus. The alterations in respiratory physiology has been attributed to Progesterone, which was thought to increase ventilation by increasing respiratory center sensitivity to carbon dioxide as a result the tidal volume and minute ventilation is increased.1,2,3 Earlier studies have documented changes in pulmonary functions using spirometry in different trimesters of pregnancy. There is less information on standard predicted or desired values in all three trimesters of pregnancy. Correlation with progesterone and pulmonary functions was not undertaken in a large scale. This study was done to evaluate the pulmonary function parameters using spirometry in primigravidae, and to correlate with their progesterone levels.
Aim and Objectives of the Study
The aim of the study is to assess, compare and correlate the pulmonary function parameters (FVC, PEFR) in primigravidae of age group between 18 and 25 with Progesterone. To formulate norms on predicted or desired values in all trimesters of pregnancy.
Materials and Methods
A total of 120 subjects were taken for the study. The subjects were from the obstetrics OPD from Meenakshi medical college. Ethical committee approval was obtained. Written informed consent was taken from the subjects. These subjects were divided into four study groups. Each group containing 30 subjects.
Control group
Group 1: Non-pregnant women, Study group: Group 2: Primigravidae in 1st trimester, Group 3: Primigravidae in 2nd trimester, Group 4 – Primigravidae in 3rd trimester.
Inclusion criteria
Healthy normal Primigravidae of Kanchipuram population in the age group 18 to 25 years and nulliparous women in the same age group. All pregnant females had a haemoglobin above 10 gm%.
Exclusion criteria
Subjects with Chronic respiratory illness, Hypertension, Diabetes mellitus (Type I, II), Pregnancy induced hypertension, Endocrine disorders, Acute and chronic CVS diseases, multiple pregnancies were avoided.
Methodology
Examination proforma used for recording the clinical examination findings was clinically well designed and validated. Computerized data logging Spirometer was used for recording the pulmonary function tests and the make was (RMS- Helios spirometer). They were assessed during morning hours (9am to 12 noon). Vital parameters and anthropometric measurements were taken. FVC and PEFR was recorded using computerised spirometer. Progesterone assay was done using CLIA.
Statistical analysis: Comparisons were performed using unpaired student’s t-test for 2 group comparisons and one way Anova was employed for multiple groups. Version SPSS 21 was used for analysis. The p value of 0.05 or less was depicted as significant. Pearson’s correlation method was used to correlate.
Result
FVC
Decrease in FVC in 1st (p<0.000), 2nd (p<0.000) and 3rd (p<0.000) trimesters of pregnancy when compared to control group was significant. In between the three trimesters there was no significant decrease (p> 0.05) in FVC values. There was significant and positive correlation of FVC and progesterone in the first and third trimester of pregnancy.
PEFR
Decrease in PEFR levels in 1st (p<0.000), 2nd (p<0.000) and 3rd (p<0.000) trimesters of pregnancy was significant when compared t o control group. Amongst the three trimesters there was significant decrease (p<0.001) in third trimester when compared to 1st and 2nd trimester. There was significant and positive correlation with the progesterone in the first trimester of pregnancy.
Table 1
Comparison of anthropometric measurements
Table 2
Comparison of pulmonary function parameters
Table 3
Comparison of cardiovascular parameters
Table 4
Comparison of pulmonary function parameters
Table 5
Correlation of pulmonary function parameters and progesterone
There is a positive correlation in all 3 trimesters of pregnancy and significant in 1st and 3rd trimester
Discussion
Pulmonary function parameters
Forced vital capacity: Present study showed significant decrease in FVC in all three trimesters of pregnancy in comparison to controls. I trimester showed significant decrease, when compared to controls, which may be due to progesterone. Decrease in FVC could be due to a decrease in the negativity of the intrapleural pressure due to upward displacement of the dia phragm by the enlarging uterus.4 This finding concurred with the study by Anita Teli et al. A study by Dipok Kumar Sunyal on forced vital capacity in pregnant women showed reduced FVC in all trimesters when compared to controls and maximum decrease in third trimester. The decrease in FVC was attributed to the mechanical pressure of enlarging gravid uterus, elevating the diaphragm & restricting the movements of lungs thus hampering the forceful expiration.5 Deepal et al., showed no significant changes in FVC during all trimesters of pregnancy. Hormonal alteration in pregnancy could have caused a reduction in the tracheo-bronchial smooth muscle tone.6 The increased thoracic width could be due to enlarging uterus as a result there was no impairment in large airway function throughout pregnancy. There was significant correlation between Progesterone and FVC in first and third trimester of pregnancy. Rarthana et al from their study suggested that the improvement in pulmonary functions in luteal phase of menstrual cycle was due to increase in progesterone levels.
Peak expiratory flow rate: In our study there was a significant decrease in PEFR in all three trimesters when compared to control group. The decrease in PEFR could be due to gravid uterus and lesser force of contraction of the expiratory muscles like anterior abdominal muscles & internal intercostals muscles.7,8 Neeraj et al., opined that the decrease in PEFR in third trimester was due to the decline in alveolar, pCO2 which acts as bronchoconstrictor. Sunyal DK et al., attributed that there was decrease in PEFR in all trimesters of pregnancy which was significant in second and third trimesters of pregnancy. Progressively reduced value of PEFR in three trimesters of pregnancy may be attributed to the mechanical effects of enlarged gravid uterus reducing vertical dimension by limiting movement of diaphragm.8 In addition some degree of obstruction to the expiratory flow, especially late in pregnancy also must have contributed.9 Our study concurred with his findings. There was significant correlation between PEFR and Progesterone in first trimester of pregnancy.
In this study the significant decrease in FVC and PEFR could be due to the mechanic al pressure of enlarging uterus which elevates the diaphragm and thus restricting the movements of lungs during forceful expiration. Decrease in PEFR also could be due to lesser force of contraction of main expiratory muscles like the anterior abdominal wall muscles and internal intercostal muscles. There was gradual increase in progesterone levels in all three trimesters. This also indirectly stimulates the secretion of endogenous catecholamines thereby through sympathomimetic action causes bronchodilatation. Though there is enlargement of uterus, progesterone effect tries to balance the restrictive changes in pregnancy.
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