Table 1.
Influence of sex steroids on the lung at different life stages in humans
| Age/time frame | Lung anatomy and physiology | Observed sex difference | Refs. |
|---|---|---|---|
| 16–26 wk gestational age (canalicular phase of lung development) | Fetal breathing movements; bronchial lumens enlarge; vascularization of lung tissue. Respiratory bronchioles and alveolar ducts develop from terminal bronchioles (wk 24). | Females exhibit mouth movements earlier than males. | 32 |
| 26–36 wk gestational age (saccular phase of lung development) | Establishment of blood-air interface (respiratory epithelium with type I and II alveolar cells); surfactant production; terminal sacs form and expand; overall increase in lung volume. | Females produce surfactant earlier than males. | 35, 36 |
| 36 wk (first postnatal week) | Alveoli form and multiply; increased FEF and decreased airway resistance. | Females have smaller lungs and lower specific airway resistance than males. | 37, 41, 42 |
| Up to 1 yr of age | Lung grows linearly with age and airway resistance increases rapidly; alveolar multiplication continues. | Females have higher FEF rates than males. | 32, 37, 38, 42 |
| Prepubertal childhood years (1–10 yr) | Alveolar multiplication continues (up to 2 yr); lung growth is dysanaptic. | Females have larger airways in relation to lung size and lower specific resistance than males. | 30, 34, 491 |
| Female lungs are smaller overall as compared to males. | 37, 42 | ||
| Large airways grow proportionately to lung in females, this growth lags in males. Smaller airways grow faster in females as compared to males. | 48 | ||
| Adolescence, puberty (10–18 yr) | Lung growth increases with age (FVC and TLC). | Female growth velocity for FVC peaks sooner than males. Specific airway resistance decreases in females up to 18 yr but not in males. Higher effort independent flows in women than men. | 37, 42, 52, 492 |
| Adults (20–70 yr) | Peak expiratory flow, FEV1, and transpulmonary pressure decrease with age; decrease in lung elastic recoil, vital capacity, chest wall compliance; increased residual volume and FRC; overall increase in airway conductance with age. | Males have higher PEF than women; higher airway conductance in males than females; no observed differences in elastic recoil or chest wall compliance. | 56, 57, 87, 493, 494 |
| Pregnancy (8–36 wk) | No changes in FVC, FEV1, VC, airway resistance, or lung compliance throughout term (12 wk to 4 months postpartum). | 53, 54 | |
| Pregnancy (third trimester) | TLC and FRC decreased at 36 wk gestation; increase in inspiratory capacity in third trimester; increase in specific airway conductance (returns to normal 5 wk postpartum); 50% reduction in total pulmonary resistance. | 53, 54 |
PEF, Peak expiratory flow.