  A massive molecular cloud complex represents local gravitational potential
that can constrain the vertical distribution of surrounding stars and gas. This
pinching effect results in the local corrugation of the scale height of stars
and gas which is in addition to the global corrugation of the mid-plane of the
disc. For the first time, we report observational evidence for this pinching on
the \HI vertical structures in the Galactic region ($20^{\circ}<
l<40^{\circ}$), also called W41--W44 region. The \HI vertical distribution is
modelled by a double Gaussian profile that physically represents a narrow dense
gas distribution confined to the mid-plane embedded in a wider diffuse \HI. We
find that the estimate of the \HI scale height distribution of wider
components, shows corrugated structures at the locations of molecular
complexes, as theoretically predicted in literature. While the narrow component
is less affected by the pinching, we found a hint of the disc being disrupted
by the active dynamics in the local environment of the complex, e.g., supernova
explosions. Molecular complexes of mass of several $10^6$ solar mass,
associated with the mini-starburst region W43 and the supernova remnant W41
show the strongest evidence for the pinching; here a broad trough, with an
average width of $\sim400$ pc and height $\sim300$ pc, in the disc thickness of
the wider component is prominently visible. Searching for similar effect on the
stars as well as in the location of other complexes in the Milky Way and other
galaxies will be useful to establish this phenomenon more firmly.
