As the first two comments mention, the question is too broad in scope. But some clarifications and variations might continue to help. :))
- In July exports declined. [Simple, direct - but changes the meaning as it's up to the reader to know if the decline continued from before.]
These are progressively worse for many reasons:
- In July exports continued declining. [a bit sloppy]
- In July exports continued their decline. [their is redundant]
- Continuing their decline, exports went down again in July. [verbose]
- Pregnant women continuing to drink alcohol despite warnings from medical experts ... [incomplete sentence fragment]
Since that's a fragment, we can only guess what the rest might need. So the meaning changes depending:
Pregnant women, who continue drinking alcohol despite warnings from medical experts, are at higher risk for (whatever). [Clean, clear]
Pregnant women are continuing to drink alcohol despite warnings from medical experts. [Progressive form. In the present, still 'happening'. Every pregnant women is drinking during pregnancy - we have a public health crisis!]
- Pregnant women have continued to drink alcohol despite warnings from medical experts. [Present, statement of fact - it's still a problem, but using Present over Progressive makes it feel more formal, less immediate. This is subtle. I think 'continued drinking' would also be common.]
So in summary, let's rephrase the two example sentences you gave.
In July exports of goods continued to decline.
In July exports of goods were still on the decline.
[The were, and still are, declining. They continue the previous decline.]
Pregnant women continuing to drink alcohol despite warnings ...
Let's say a reasonable guess is ...
Drinking alcohol during pregnancy causes problems. If you don't listen to the warnings, then ...
Pregnant women continuing to drink alcohol despite warnings need to have their heads examined.
" women continuing to drink alcohol despite warnings" is a noun phrase, which shortens to: "They need to have their heads examined."